In \triangle A B C, A B=A C=28 and B C=20. Points D, E, and F are on sides \overline{A B}, \overline{B C}, and \overline{A C}, respectively, such that \overline{D E} and \overline{E F} are parallel to \overline{A C} and \overline{A B}, respectively. What is the perimeter of parallelogram A D E F ?
Answer Choices
A. 48
B. 52
C. 56
D. 60
E. 72
