Some Protostars, When They Evolve onto the Main Sequence, Are

Some protostars, when they evolve onto the main sequence, are fully convective and use convection to transport material all the way from the core to the surface. Which stars show this characteristic?

A) only the smallest, of less than about 0.4 solar mass
B) intermediate stars, of about 0.4 solar mass up to about 4 solar masses
C) the largest, of more than about 4 solar masses
D) all protostars