The answer is c.) doctor's
To show procession of the patients by the doctor add 's to the word doctor.
I- I would love something like that..
The answer would be D the year the source was published.
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.