The Apollo 13 mission of 1970, a nearly catastrophic spaceflight that tested the limits of human ingenuity and _____ demonstrated...

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 Apollo 13 mission of 1970,
  • a nearly catastrophic spaceflight
    • that tested the limits of
    • human ingenuity and resilience [?],
• demonstrated NASA's ability to respond effectively to life-threatening
• emergencies in space.

• Where [?] represents:
  • A: , and
  • B: ,
  • C: and
  • D: [nothing]

Understanding the Meaning

Let's start reading from the beginning:

'The Apollo 13 mission of 1970,'

• This is what we're talking about - a specific NASA mission from 1970.
• The comma signals that more descriptive information is coming.

'a nearly catastrophic spaceflight that tested the limits of human ingenuity and resilience'

• This is describing what that mission was like
• 'Nearly catastrophic' means it almost ended in disaster
• It tested human ingenuity (creative problem-solving) and resilience (ability to persevere through difficulties)

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

• They vary in whether we have a comma, "and," both, or neither after "resilience"

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

'demonstrated NASA's ability to respond effectively to life-threatening emergencies in space.'

• This is telling us what the mission showed or proved
• It demonstrated (showed) that NASA could handle dangerous emergencies

Now let's understand the complete structure:

What do we notice about how this sentence is built?

• The core sentence is actually:
  "The Apollo 13 mission of 1970 demonstrated NASA's ability..."
• Everything in the middle - "a nearly catastrophic spaceflight that tested the limits of human ingenuity and resilience" - is extra descriptive information
  • It's giving us more details about the mission
  • But it's interrupting the main flow from subject to verb
• This interrupting description needs to be set off with paired commas:
  • Opening comma after "1970" signals: "here comes extra info"
  • Closing comma after "resilience" signals: "extra info is done, back to main sentence"

The pattern is: Subject, interrupting description, verb...

So we need just a comma after "resilience" to close off the interrupting phrase.

The correct answer is Choice B (resilience,) - just the comma, no "and."

GRAMMAR CONCEPT APPLIED

Using Paired Commas with Interrupting Descriptive Phrases

When extra descriptive information interrupts the main flow of a sentence - especially between the subject and verb - you need to set off that interruption with paired commas (called a non-restrictive appositive or non-essential modifier in grammar terms).

The Pattern:

Main sentence core: The Apollo 13 mission demonstrated NASA's ability

Interrupting description added: The Apollo 13 mission of 1970, a nearly catastrophic spaceflight that tested the limits of human ingenuity and resilience, demonstrated NASA's ability...

How it works:

• Opening comma (after "1970") = signals "extra info starting"
• Interrupting phrase = provides descriptive details about the subject
• Closing comma (after "resilience") = signals "extra info ending, back to main sentence"
• Main verb continues = "demonstrated..."

Why paired commas?

• They work like parentheses - what's inside could be removed and the sentence would still be complete
• Test: "The Apollo 13 mission of 1970 demonstrated NASA's ability..." Complete!

Common mistake to avoid:

• Don't use "and" before the main verb - "and" connects parallel elements, not a description to the main action

In this question:

• Subject: "The Apollo 13 mission of 1970"
• Interrupting description: "a nearly catastrophic spaceflight that tested the limits of human ingenuity and resilience"
• Needs closing comma after "resilience"
• Then continues with main verb: "demonstrated"