In trapezoid A B C D we have \overline{A B} parallel to \overline{D C}, E as the midpoint of \overline{B C}, and F as the midpoint of \overline{D A}. The area of A B E F is twice the area of F E C D. What is A B / D C ?
Answer Choices
A. 2
B. 3
C. 5
D. 6
E. 8