The problem with A is that it is too 'coincidental'. It reduces the end of Sauron to a fluke. For an 'accident' to save the whole world from disaster seems beyond belief. There must have been a purpose behind it, or it kind of makes all the struggles up to that point 'pointless'.
The problem with B is that it makes Eru a murderer.
The problem with C is that he
didn't jump.
The problem with D is that it doesn't actually make sense
I go for option
n....