You can find the ______ by asking yourself who or what carries out the action of the verb.

A.verb
B. prepositional phrase
C.helping verb
D.subject

Which answer do you think is correct?

...who or what carries out the action of the verb

Yes, D is correct.

The answer is D. subject. To determine the subject of a sentence, you need to ask yourself who or what is carrying out the action of the verb.

Here's an example to help illustrate this concept:
Sentence: "Sara sings beautifully."

To find the subject in this sentence, you would ask yourself, "Who or what is carrying out the action of the verb 'sings'?" In this case, the answer is "Sara." Therefore, "Sara" is the subject of the sentence.

By identifying the subject, you can understand who or what is performing the action in a sentence.