A Main-Sequence Star Has a Certain Lifetime, T, Because of Thermonuclear

Multiple Choice

A main-sequence star has a certain lifetime, t, because of thermonuclear "burning" of the hydrogen in the core of the star. How is this lifetime on the main sequence related to the mass M and luminosity L of the star? ( $\alpha$ means "proportional to")

A) t M/L $\alpha$
B) t ML $\alpha$
C) t L/M $\alpha$
D) t M^3.5 $\alpha$