According to Naomi Nakayama of the University of Edinburgh, the reason seeds from a dying dandelion appear to float in...

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

• According to Naomi Nakayama of the University of Edinburgh,
  • the reason
    • seeds from a dying dandelion
      • appear to float in the air
        • while falling[?]
  • is that
    • their porous plumes enhance drag,
      • allowing the seeds to stay airborne long enough
        • for the wind to disperse them throughout the surrounding area.
• [?] = comma, colon, semicolon, or nothing

Understanding the Meaning

Let's start reading from the beginning:

"According to Naomi Nakayama of the University of Edinburgh,"

• This tells us who the expert is and where she works.

The sentence continues: "the reason seeds from a dying dandelion appear to float in the air while falling..."

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

• A. falling, (with a comma)
• B. falling: (with a colon)
• C. falling; (with a semicolon)
• D. falling (no punctuation)

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

The sentence continues: "is that their porous plumes enhance drag, allowing the seeds to stay airborne long enough for the wind to disperse them throughout the surrounding area."

Now let's understand the complete meaning:

• Seeds from a dying dandelion seem to float while they're falling
• The REASON they float is that their porous (filled with tiny holes) plumes create drag
• This drag keeps them in the air long enough for wind to spread them around

So the sentence is explaining WHY dandelion seeds float as they fall.

What do we notice about the structure here?

• The sentence follows this pattern:
  • "the reason [something happens] is that [explanation]"
• More specifically:
  • Subject: "the reason seeds from a dying dandelion appear to float in the air while falling"
  • Verb: "is"
  • Explanation: "that their porous plumes enhance drag..."
• The word "falling" is at the END of a long subject
  • The entire phrase from "the reason" through "while falling" is describing ONE thing - the floating phenomenon being explained
  • This whole phrase is the subject of the sentence
• Right after this subject comes the verb "is"

Here's the key: A subject and its verb should connect directly to each other without any punctuation between them - even when the subject is really long.

So we need: D. falling (no punctuation)

This allows "the reason seeds from a dying dandelion appear to float in the air while falling" to connect properly to its verb "is."

Grammar Concept Applied

Keeping Subjects and Verbs Connected

One of the most fundamental rules in English grammar is that a subject and its verb must connect directly without punctuation between them. This is true even when the subject is very long or complex.

The pattern:

• ✓ CORRECT: [Subject, however long] + [verb] + [rest of sentence]
• ✗ INCORRECT: [Subject] + comma/colon/semicolon + [verb]

Examples:

1. Simple subject (easy to see):
   • ✓ The cat is sleeping.
   • ✗ The cat, is sleeping.
2. Longer subject (still no punctuation before verb):
   • ✓ The cat that lives next door is sleeping.
   • ✗ The cat that lives next door, is sleeping.
3. Very long subject (tempting to add punctuation, but don't!):
   • ✓ The reason birds migrate south during winter months is that food becomes scarce in colder climates.
   • ✗ The reason birds migrate south during winter months, is that food becomes scarce in colder climates.

How this applies to our question:

In our sentence, we have a very long subject: "the reason seeds from a dying dandelion appear to float in the air while falling"

Even though this subject is long and contains multiple parts, it must connect directly to its verb "is" without any punctuation. The length of the subject doesn't change this fundamental rule - subjects and verbs stay together.