The correct option in C and your right
The explanation : 0 is the identity element of addition because an identity element means when we do any operation to a set of numbers with the identity we get the same number.
identity element for multiplication is 1 as 8*1=8 the number itself
and according to your question. In addition 0+10000=10000 the number itself
So 0 is the identity element under addition
Hope your satisfied with the answer :)