8. Let f be the function defined below, where c and d are constants. If f is differentiable at x=1, what is the value of c-d?

f (x) = x^2 + (2c +1)x − d, x ≥ −1
e(^2x+2) + cx + 3d, x < -1
A. -2
B. 0
C. 2
D. 3
E. 4