Identify a sentence that contains an action verb

1)She walked to the store with her best friend.
2) I am sometimes grumpy when I'm hungry.
3) They are heavier than they were before.
4) He is a major league baseball player.

And you think it's ... ?

No.

https://www.gallaudet.edu/tutorial-and-instructional-programs/english-center/grammar-and-vocabulary/verbs/action-verbs-and-linking-verbs

Read carefully so you learn the difference between action verbs and linking verbs. Then re-read those sentences with those definitions in mind. Don't guess.

The sentence that contains an action verb is: "She walked to the store with her best friend."

To identify a sentence that contains an action verb, you need to look for a word in the sentence that describes an action. In this case, the word "walked" is the action verb because it describes the physical movement of "she" to the store.