The answer is B) 8.
We can tell this because the discriminant is equal to b^2 - 4ac. We know a = -1 (the coefficient of x^2), b = 4 (the coefficient of x) and c = -2 (the number on the end). Then we plug in.
b^2 - 4ac
(4)^2 - 4(-1)(-2)
16 + 4(-2)
16 - 8
8
