Which sentence includes a gerund?

1. Swimming in the gulfs is Finn’s favorite some activity.
2. Grandma learned a dive at a community, swimming pool
3. While swimming at the beach, Harper found a starfish.
4. Nash has been swimming since he was five years old.

3. While swimming at the beach, Harper found a starfish.

The sentence that includes a gerund is:

3. While swimming at the beach, Harper found a starfish.

In this sentence, the word "swimming" is a gerund, which functions as the subject of the sentence.

To identify the sentence that includes a gerund, we need to understand what a gerund is. A gerund is a verb form that acts as a noun and usually ends in "-ing."

Let's analyze the given options:

1. "Swimming in the gulfs is Finn’s favorite some activity."
This sentence does include the word "swimming," which ends in "-ing." However, it is used as part of a descriptive phrase rather than functioning as a noun. Therefore, it is not a gerund.

2. "Grandma learned a dive at a community, swimming pool."
In this sentence, the word "swimming" is used as an adjective to describe the type of pool, so it is not a gerund.

3. "While swimming at the beach, Harper found a starfish."
Here, the word "swimming" is functioning as the subject of the sentence. It is a noun form derived from the verb "swim" and ends in "-ing." This makes it a gerund.

4. "Nash has been swimming since he was five years old."
In this sentence, "swimming" is used as part of the verb phrase "has been swimming" and is not acting as a noun. Therefore, it is not a gerund.

Based on this analysis, the sentence that includes a gerund is:
3. "While swimming at the beach, Harper found a starfish."