In the context of an adjective used to describe pain, we can look at the answer choices:
Silent pain seems like an odd choice for someone to notify a doctor about, so that is probably not the answer.
Thoughtful does not describe pain.
Responsive does not describe pain.
Severe pain would be a reason for someone to notify a doctor, so this is likely the correct answer choice.
I think the anwser is D, but i remember Animal Farm I hated that book.
The answer to this question will be C