the chairmen of congressional committees are chosen by
a. the vote of committee members
b. seniority
c. the vote of the majority party
d. the speaker of the house
b
http://edsitement.neh.gov/view_lesson_plan.asp?id=284
Read carefully -- especially in section 3.
To find the answer to this question, we can start by understanding the process of selecting chairmen for congressional committees.
The chairmen of congressional committees are chosen based on a combination of factors, but the primary factor traditionally has been seniority. Seniority refers to the length of service of a member in Congress. Generally, the member who has served on a committee for the longest period of time within their party is likely to become the chairperson of that committee. This system of seniority is often used in both houses of Congress, the House of Representatives, and the Senate.
So, option (b) "seniority" is the correct answer to the question.