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: 1. Degree and graduated
Explanation:
Everyone 
done his or her homework.
Explanation:
Everyone is singular and, therefore, require singular verb.
Answer:
C. It explains one way rain barrels benefit you, and one way rain barrels benefit plants.
Answer: A). People can have a big impact on others' lives without realizing it.
Explanation: The other options seem worthy as well but this one is the appropriate choice.
