The 2022 Nobel Prize in Chemistry was awarded to three pioneers in the field of click chemistry: two-time Nobel laureate...

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 2022 Nobel Prize in Chemistry
  • was awarded to three pioneers in the field of click chemistry:
    • two-time Nobel laureate Barry Sharpless,
      • who coined the term 'click chemistry' in 1998;
    • Carolyn Bertozzi,
      • founder of the Bertozzi Group at Stanford(?);
    • and Morten Meldal,
      • a professor at the University of Copenhagen in Denmark.

Understanding the Meaning

The sentence starts by telling us about an award:

• The 2022 Nobel Prize in Chemistry
  • was given to three pioneers in click chemistry

Then we get a colon, which signals that the sentence is about to list these three pioneers:

First person:

• "two-time Nobel laureate Barry Sharpless,"
  • Barry Sharpless is identified as a two-time Nobel laureate
  • Additional detail: "who coined the term 'click chemistry' in 1998"
  • This description ends with a semicolon

Second person:

• "Carolyn Bertozzi,"
  • She's identified as "founder of the Bertozzi Group at Stanford"
  • This is where we have the blank

Let's look at the choices:

• We need to decide what punctuation (if any) should follow "Stanford"
  • Choice A: no punctuation
  • Choice B: comma
  • Choice C: colon
  • Choice D: semicolon

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

Third person:

• "and Morten Meldal,"
  • Identified as "a professor at the University of Copenhagen in Denmark"
  • The sentence ends with a period

Now let's look at the complete structure. What do we notice?

• This is a three-item list introduced by the colon:
  • Item 1: Barry Sharpless (with his description)
  • Item 2: Carolyn Bertozzi (with her description)
  • Item 3: Morten Meldal (with his description)
• Each item contains its own commas:
  • "two-time Nobel laureate Barry Sharpless, who coined..."
  • "Carolyn Bertozzi, founder of..."
  • "Morten Meldal, a professor..."
• The first item ends with a semicolon
• The third item begins with "and"

This tells us the pattern:

• When list items are complex and contain their own internal commas,
  • we use semicolons to separate the major list items
  • this keeps things clear - we can tell which commas are within an item's description and which marks separate the main items
• The pattern here is: Item 1; Item 2; and Item 3

So we need a semicolon after Stanford to match the structure. The correct answer is Choice D: Stanford;

GRAMMAR CONCEPT APPLIED

Using Semicolons to Separate Complex List Items

When you have a list where each item contains its own commas or other internal punctuation, use semicolons to separate the major items (this is called a complex series). This creates clear boundaries between the main elements:

Simple list (items without internal commas):

• We invited Maria, John, and Sarah.
  • Commas work fine here because each item is simple

Complex list (items with internal commas):

• We invited Maria, our neighbor from Boston; John, my college roommate; and Sarah, the team captain.
  • Semicolons separate the three people
  • Commas within each item provide additional description

The pattern:

• Item 1 (with internal comma); Item 2 (with internal comma); and Item 3 (with internal comma).

In our question:

• Barry Sharpless, who coined the term 'click chemistry' in 1998;
• Carolyn Bertozzi, founder of the Bertozzi Group at Stanford;
• and Morten Meldal, a professor at the University of Copenhagen

Each person's description contains commas, so semicolons separate the three main list items, keeping the structure clear and organized.