Question about Rigor Mortis

This is the question I was given:

Rigor mortis     

a. ends when ATP binds the myosin heads
b. is muscular rigidity resulting from a lack of acetylcholinesterase
c. is caused by muscular degradation following death
d. is initiated by the leakage of calcium from the SR
e. none of the above is true

I know it's not A nor C because the reason why rigor mortis occurs is because a dead body cannot produce ATP and muscular degradation is what stops rigor mortis.

I'm stuck between D or E. I feel like it may be D because even after death some calcium could leak out if the calcium gates aren't completely closed.

Please help!