Recent analysis of 32532 Thereus—an outer solar system object orbiting the Sun between Jupiter and Saturn—has determined its color to...

Let's begin by understanding the meaning of this sentence. We'll use our understanding of pause points and segment the sentence as shown - understanding and assimilating the meaning of each segment bit by bit!

Sentence Structure

• Recent analysis of 32532 Thereus
  • -an outer solar system object
    • orbiting the Sun
      • between Jupiter and Saturn-
• has determined its color to be gray,
  • suggesting an icy composition.

• Such interpretations are ultimately ______ the object's gray coloration
  • may be an incidental effect
    • of radiation,
      • solar wind,
        • or collisions with other objects
    • rather than evidence of its physical makeup.

• Blank shows: speculative[?]though[?]
  • (where [?] represents the punctuation we need to determine)

Understanding the Meaning

Let's start with the first sentence to get context:

Recent analysis has determined the color of this space object (32532 Thereus) to be gray, which suggests it might be made of ice.

Now the second sentence:
‘Such interpretations are ultimately...’

This is where we have the blank. Let's look at the choices:

• A. speculative, though
• B. speculative, though;
• C. speculative; though
• D. speculative, though,

All choices have the word "speculative" and the word "though" - we're deciding how to punctuate around these words.

To see what works here, let's read the rest of the sentence and understand what it's saying!

The sentence continues:
‘the object's gray coloration may be an incidental effect of radiation, solar wind, or collisions with other objects rather than evidence of its physical makeup.’

Now let's understand what this complete sentence is telling us:

• ‘Such interpretations are ultimately speculative’
  • The interpretations (that the object is icy based on its gray color) are speculative - meaning they're educated guesses, not certain facts.
• ‘though’
  • This word adds a qualifying, somewhat concessive tone - like saying "mind you" or "to be fair"
• ‘the object's gray coloration may be an incidental effect...’
  • This explains WHY the interpretations are speculative:
    • The gray color might not actually tell us about composition at all
    • It might just be caused by external factors like radiation or collisions
    • Rather than being evidence of what the object is made of

So the complete picture is:

• These interpretations are just educated guesses, and here's why: the gray color might be caused by other things entirely.

What do we notice about the structure here?

• ‘Such interpretations are ultimately speculative, though’
  • This is a complete thought - it can stand alone as a sentence.
  • The word "though" at the end is part of this thought, adding a concessive qualifier.
• ‘the object's gray coloration may be an incidental effect...’
  • This is ALSO a complete thought - it has its own subject (the object's gray coloration) and verb (may be).
  • It can stand alone as a sentence too.

When we have two complete thoughts that we want to keep in the same sentence, we need strong punctuation to separate them properly - specifically, a semicolon.

So we need: speculative, though;

The answer is Choice B.

• The comma before "though" keeps it connected to the first part
• The semicolon after "though" properly separates the two complete thoughts

GRAMMAR CONCEPT APPLIED

Separating Two Complete Thoughts with a Semicolon

When you have two complete thoughts (each with its own subject and verb that could stand alone as sentences), you need strong punctuation to separate them if you want to keep them in one sentence. A semicolon does this job.

The pattern:

• First complete thought: The experiment failed
• Second complete thought: The results were inconclusive
• Combined with semicolon: The experiment failed; the results were inconclusive.

You can also have words that are part of the first thought before the semicolon:

• First complete thought with qualifier: The experiment failed, unfortunately
• Second complete thought: the results were inconclusive
• Combined: The experiment failed, unfortunately; the results were inconclusive.

In our question:

• First complete thought: Such interpretations are ultimately speculative, though
  • "though" is part of this thought, adding a concessive tone
• Second complete thought: the object's gray coloration may be an incidental effect...
• Combined correctly: Such interpretations are ultimately speculative, though; the object's gray coloration may be...

The semicolon is essential here because both parts can stand alone as complete sentences (called independent clauses in grammar terms). Without the semicolon, you'd have incorrectly punctuated sentences like comma splices or run-ons.