Because a is the first letter in the alphabet
I believe the answer is C) frightened. A participle is a word formed from a verb, and used an an adjective or a noun. Since frightened and climbed are both verbs, that narrows it down to either C or D. From there, frightened is an adjective, while climbed is nor an adjective or a verb.
Answer:
I love autumn it is my favorite season- c.
