Main-Sequence Stars Can Be Divided into Those with More Than

Main-sequence stars can be divided into those with more than 75% of the mass of the Sun and those with less than this amount of mass.What is different about these two groups?

A) The less massive group does not have enough mass to undergo nuclear fusion.
B) Stars in the less massive group are all fully convective.
C) Stars in the less massive group are all free floating bodies that have never been part of a binary system.
D) Some of the stars in the more massive group have evolved off the main sequence, while none of the stars in the less massive group have done so.