2001 AMC 12 Problem 13

The parabola with equation y=ax^2+bx+c and vertex (h,k) is reflected about the line y=k. This results in the parabola with equation y=dx^2+ex+f. Which of the following equals a+b+c+d+e+f?

\text{(A) }2b \qquad \text{(B) }2c \qquad \text{(C) }2a+2b \qquad \text{(D) }2h \qquad \text{(E) }2k

Full credit goes to MAA for authoring these problems. These problems were taken on the AOPS website.