What is the most reliable way to get the opinions of experts on any writing topic?

A. Call them to set up interviews.

B. Do research at a library.

C. Contact them on the Internet.

D. Write to them and hope for an answer.

Calling up experts and setting them up in interviews is the most reliable way to get the opinions of experts on any writing topic. Because in this type of source, you get the first-hand information from someone who has a forte on that certain area.