Do SAT coaching classes work? Do they help students to improve their test scores? Four students were selected randomly from all of the students that completed an SAT coaching class. For each student, we recorded their first SAT score (before the class) and their second SAT score (after the coaching class).

		Student
		1	2	3	4
First SAT score	920	830	960	910
Second SAT score	1010	800	1000	980

To analyze these data, we should use

Choose the best answer below:

A. the two-sample t test.

B. the one-sample t test.

C. Any of the above are valid. It just needs to be a t since is unknown.

D. the matched pairs t test.