This question tests the understanding of the word 'prescribe' in a medical context. The correct answer is B, as 'prescribe' means to recommend or authorize the use of a medicine or treatment for someone, especially in writing. Option A is incorrect because diagnosing a disease is a different process from prescribing treatment. Option C is unrelated to the meaning of 'prescribe'. Option D is incorrect because conducting research is not what 'prescribe' means.