Whose DNA Will Be Most Similar to Bob's? Arrange Them

Multiple Choice

Whose DNA will be most similar to Bob's? Arrange them in order,from most similar to least similar: mother,sibling,grandfather,identical twin.

A) identical twin,mother,sibling,grandfather
B) grandfather,sibling,mother,identical twin
C) mother,sibling,identical twin,grandfather
D) identical twin,sibling,grandfather,mother
E) none of the above