The answer is B: sick or weak.
Striken means critically affected by an annoying condition or bad feeling. In the sentence from paragraph four, the word stricken implies that the person displays an unpleasant expression in his face, as if he were a wounded animal.
Options A and D are incorrect because they are not synoyms of stricken. Option C is not possible either because of the animal reference, which would not allow feelings of sadness.