As a behavioral economist, Katy Milkman of the University of Pennsylvania recognizes that people sometimes make irrational economic decisions. Milkman...

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

• As a behavioral economist,
  • Katy Milkman of the University of Pennsylvania
    • recognizes
      • that people sometimes make irrational economic decisions.
• Milkman's research
  • can thus address anomalies
    • that neoclassical economic models [?] which assume that people
      • are consistently rational decision-makers [?]
        • cannot explain.

Understanding the Meaning

The first sentence sets up the context:

• 'As a behavioral economist, Katy Milkman of the University of Pennsylvania recognizes that people sometimes make irrational economic decisions.'
  • This tells us Milkman's field and her key insight
  • People don't always make rational economic choices

Now the second sentence tells us the significance of Milkman's research:

• 'Milkman's research can thus address anomalies'
  • "Thus" = because she understands irrationality
  • She can explain anomalies (things that don't fit the expected pattern)

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

• The punctuation varies around the phrase "which assume that people are consistently rational decision-makers"

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

• 'that neoclassical economic models... cannot explain'
  • This is describing what anomalies we're talking about
  • Anomalies that traditional economic models can't explain

So putting it together, the structure is:

• 'anomalies that neoclassical economic models [description of the models] cannot explain'

Now let's understand what this middle part is doing:

• 'which assume that people are consistently rational decision-makers'
  • This describes what neoclassical models assume
  • They assume people are always rational

The complete meaning:

• Milkman's research can explain problems that traditional economic models (which assume people are always rational) can't explain
• This makes sense because Milkman recognizes people are sometimes irrational, while traditional models don't account for that

What do we notice about the structure here?

• The phrase "which assume that people are consistently rational decision-makers" is:
  • Additional information about the models (non-essential - we could remove it and the sentence would still work)
  • Interrupting the flow from "models" to "cannot explain"
• We have: "models" ... [interrupting information] ... "cannot explain"
  • The subject "models" is separated from its verb "cannot explain"

When you have non-essential information that interrupts between related parts of a sentence, you need matching punctuation on both sides - like putting the interruption in a container.

So we need: matching dashes (or matching commas, but dashes work better for substantial interruptions like this one).

The correct answer is A: models—which ... decision-makers—cannot

GRAMMAR CONCEPT APPLIED

Using Matching Punctuation to Set Off Interrupting Information

When you insert descriptive information that:

• Is non-essential (could be removed without breaking the sentence)
• Interrupts the flow between related parts (like between a subject and its verb)

You must use matching punctuation on both sides to set it off - either two commas or two dashes:

With dashes (for emphasis or longer interruptions):

• The research—which took five years to complete—changed the field
• "research" connects to "changed" (subject and verb)
• The middle part interrupts with extra information
• Matching dashes create a clear container

With commas (for simpler, shorter interruptions):

• The scientist, who worked in Boston, made an important discovery
• Same principle with commas instead of dashes

In this question:

• "neoclassical economic models" [subject] needs to connect to "cannot explain" [verb]
• "which assume that people are consistently rational decision-makers" interrupts with descriptive information
• Matching dashes properly set off this substantial interruption: models—which assume...—cannot explain