One Star in a Binary Will Almost Always Become a Red

One star in a binary will almost always become a red giant before the other because:

A) one star is always larger in radius than the other
B) binaries always have one star twice as massive as the other
C) small differences in main-sequence masses yield large differences in main-sequence ages
D) the more massive binary star always gets more mass from the less massive binary star when both are main-sequence stars
E) one star always spins faster than the other