Robin Wall Kimmerer of the Citizen Potawatomi Nation is a bryologist, a plant scientist who specializes in mosses. To Kimmerer,...

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

• Robin Wall Kimmerer of the Citizen Potawatomi Nation is a bryologist
  • a plant scientist who specializes in mosses
• To Kimmerer
  • mosses are Earth's most adaptable plants
    • they can clone themselves [?]
    • enter a dormant state in times of drought
    • and grow in areas that don't have soil
• [?] = comma, semicolon, period + "And", or nothing

Understanding the Meaning

The first sentence introduces us to Robin Wall Kimmerer:

• She's from the Citizen Potawatomi Nation
• She's a bryologist - a plant scientist who specializes in mosses

The second sentence tells us Kimmerer's perspective:

• To Kimmerer, mosses are Earth's most adaptable plants

The colon signals that what follows will show us WHY mosses are so adaptable.

Now the sentence gives us examples of what mosses can do:

• 'they can clone themselves...'

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

• Choice A: themselves;
• Choice B: themselves,
• Choice C: themselves. And
• Choice D: themselves (no punctuation)

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

The sentence continues:

• 'enter a dormant state in times of drought, and grow in areas that don't have soil.'

Now let's understand what this complete structure is telling us:

• 'they can clone themselves'
  • First ability showing adaptability
• 'enter a dormant state in times of drought'
  • Second ability showing adaptability
• 'and grow in areas that don't have soil'
  • Third ability showing adaptability

So the complete picture is:

• The sentence is listing three different abilities that demonstrate why mosses are so adaptable
• All three actions share the same structure - they all go with "they can"

What do we notice about the structure here?

• This is a list of three items in a series
  • When we list three or more items, we separate them with commas
  • The pattern is: item 1, item 2, and item 3
• In this sentence
  • Item 1: clone themselves
  • Item 2: enter a dormant state in times of drought
  • Item 3: grow in areas that don't have soil

So we need Choice B (themselves,) - a comma after "themselves" to properly separate the first item from the second item in this three-part series.

GRAMMAR CONCEPT APPLIED

Using Commas to Separate Items in a Series

When you list three or more items (whether single words, phrases, or clauses), you need to separate them with commas. The pattern uses commas between items and "and" before the final item (this comma before "and" is called the Oxford comma or serial comma in grammar terms):

Pattern: Item 1, Item 2, and Item 3

Example with single words:

• The scientist studied mosses, ferns, and lichens.

Example with phrases (like our question):

• Mosses can clone themselves, enter a dormant state in times of drought, and grow in areas that don't have soil.
  • Item 1: clone themselves
  • Item 2: enter a dormant state in times of drought
  • Item 3: grow in areas that don't have soil

Why this matters:

• The commas create clear separation between distinct items
• They help readers understand where one item ends and another begins
• They prevent confusion and maintain parallel structure in the list

In our question:

• The three abilities are all parallel verb phrases sharing "they can"
• Each needs to be separated from the next with a comma
• After "themselves" we need a comma to properly introduce the second ability in the series