A is correct.
Explanation: Because it's means it is
Its means something like theirs, itself, e.x - the dog likes to curl up in its bed.
I don’t have a sister but ok sure
It means that <span>Each night is new; previous events do not matter.
The Moon rises every night, and thus it forgets what happened the night before. This proverb sort of describes that, you shouldn't hold a grudge, just like the Moon gets over what happened previously. </span>
