The discoveries made by astronomer Vera _____ provided crucial evidence for the existence of dark matter in the universe.

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 discoveries
  • made by astronomer Vera Rubin [?]
• provided crucial evidence
  • for the existence of dark matter
    • in the universe.

Understanding the Meaning

Let's read through this sentence and understand what it's saying:

We're talking about "The discoveries"
specifically, discoveries "made by astronomer Vera Rubin"

This is where we have the blank.

Let's look at the choices:

• A. Rubin:
• B. Rubin (no punctuation)
• C. Rubin,
• D. Rubin—

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

After "Rubin" the sentence continues: "provided crucial evidence for the existence of dark matter in the universe."

So what's this sentence telling us?

• The discoveries (the ones made by Vera Rubin) did something
• They "provided crucial evidence for the existence of dark matter"

The complete picture: This is a sentence about what Rubin's discoveries accomplished - they gave us important evidence about dark matter.

What do we notice about the structure here?

• "The discoveries made by astronomer Vera Rubin" is the complete subject
  • "made by astronomer Vera Rubin" describes which discoveries
• "provided" is the main verb - the action of the sentence
  • This is what the discoveries DID
• After the describing phrase ends ("Rubin"), the sentence needs to flow directly to its main verb ("provided")

There's nothing being introduced, set off, or interrupted here - the sentence just continues naturally from the subject to its verb.

So we need no punctuation. The answer is B.

GRAMMAR CONCEPT APPLIED

Maintaining Natural Sentence Flow: Subject to Verb

When a sentence has a clear subject-verb-object structure, don't insert punctuation that would interrupt the natural flow from the subject to the main verb.

The basic pattern:

• Subject (with any describing phrases) flows directly into Main Verb
• No punctuation between them

Example 1:

• The student, who studied every night, passed the exam.
• The student who studied every night passed the exam.
• If the phrase is essential to identify which student, no commas

Example 2:

• The research conducted by the team: revealed new findings.
• The research conducted by the team revealed new findings.
• Subject with modifier → verb (no punctuation break)

In our question:

• Subject: "The discoveries"
• Describing phrase: "made by astronomer Vera Rubin"
• Main verb: "provided"
• Structure: [Subject + describing phrase] → [verb] (no punctuation)

The key is recognizing when the sentence needs to flow continuously through its core structure without any punctuation interruption.