Answer: A) Smelled.
Explanation: A linking verb is a verb that connects the subject with a word that gives information about the subject, such as a condition or relationship. In the given sentences we can see four different verbs in past form (smelled, prepared, marched and turned), but the only one that represents an example of a linking verb is "smelled" because it is giving information about the subject it is saying that the summer wind (the subject) smelled fresh (the information).