Read the following SAT test question and then click on a button to select your answer.

y = (-2x^2) + (bx) + 5

In the xy-plane, the graph of the equation above assumes its maximum value at x = 2. What is the value of b?

(A)-8
(B)-4
(C) 4
(D) 8
(E) 10

来源:可可英语 http://www.kekenet.com/sat/201411/343175.shtml