Answer:
a. DK = KE
Explanation:
We are told that DE is the perpendicular bisector of JL, therefore statement b is true.
A bisector divides a line (or an angle) into two equal parts at the line's midpoint, therefore JK = KL and K is the midpoint of JL. So statements c and d are true.
We don't know if K is the midpoint of DE. Therefore, we don't know if DK = KE, so statement a is not necessarily true.