Why Is the Building at Ise Jingu Rebuilt Every Twenty

Why is the building at Ise Jingu rebuilt every twenty years?

A) because the wood used to build it lasts precisely that long
B) because that is how long Amerataerasu Omikami lived
C) because nature is cyclical and the shrine, too, must be renewed and refreshed
D) because if rebuilding it was postponed any longer the next generation would not know how it was built
E) all of the other answers