The newly deployed space telescope captured detailed images of the distant ______ which provided astronomers with unprecedented evidence of star...

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

• The newly deployed space telescope
  • captured detailed images
    • of the distant galaxy [?]
      • which provided astronomers with unprecedented evidence
        • of star formation
          • in the early universe.

Understanding the Meaning

Let's start reading from the beginning:

'The newly deployed space telescope captured detailed images of the distant galaxy'

• A new telescope was put into space
• It took detailed pictures of a galaxy far away

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

• We need to decide what punctuation (if any) should come after "galaxy"
• The options are: nothing, a dash, a semicolon, or a comma

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

'which provided astronomers with unprecedented evidence of star formation in the early universe'

• Something "provided astronomers with unprecedented evidence"
• This evidence is about star formation in the early universe
• The key word here is "which"

Now let's understand what "which" is referring to:

• Could "which" refer to "the galaxy"?
  • That would mean the galaxy itself provided evidence to astronomers
  • But galaxies don't actively provide evidence - they just exist
• What if "which" refers to "the detailed images"?
  • That would mean the images provided astronomers with evidence
  • That makes perfect sense! The telescope captured images, and those images gave scientists important information

So the complete picture is:

• The telescope captured images of a distant galaxy
• Those images gave astronomers unprecedented evidence about star formation

What do we notice about the structure here?

The phrase starting with "which provided astronomers..." is giving us extra information about the images. It's adding a bonus detail - telling us what those images accomplished.

When we have a "which" phrase that adds this kind of supplementary information about something we just mentioned, we need a comma to introduce it. The comma signals: "Here's some additional information about what I just told you."

So we need: galaxy, (Choice D)

GRAMMAR CONCEPT APPLIED

Using Commas with "Which" Clauses That Add Extra Information

When you want to add supplementary information about something you just mentioned, you can use a clause starting with "which" (called a non-restrictive relative clause in grammar terms). These clauses must be introduced with a comma:

Pattern: [Main statement], which [additional information].

Example 1:

• Without extra info: "The researchers analyzed the fossil"
• With "which" clause: "The researchers analyzed the fossil, which dated back 65 million years"
  • Main statement: The researchers analyzed the fossil
  • Extra information: which dated back 65 million years
  • The comma introduces the bonus detail

Example 2:

• Without extra info: "The team developed a new algorithm"
• With "which" clause: "The team developed a new algorithm, which improved processing speed by 40%"
  • Main statement: The team developed a new algorithm
  • Extra information: which improved processing speed by 40%
  • The comma sets off the supplementary detail

In our question:

• Main statement: "The telescope captured detailed images of the distant galaxy"
• Extra information: "which provided astronomers with unprecedented evidence..."
• The comma after "galaxy" correctly introduces this additional information about what the images accomplished

Key signal: When "which" starts a clause that adds bonus information (information you could remove and still have a complete sentence), you need a comma before "which."