What is BD?

There is a quadrilateral ABCD in which side AB is congruent to side AD and side BC is congruent to side CD. The length of side BC is 10. The diagonal AC and the diagonal BD intersect each other at point E. The length of AE is 12, the length of EC is 8, and the length of BE is 6.

A. 10
B. 12
C. 13
D. 14