If you're a more massive MS star, why do you tend to be more lumninous than less massive MS stars?

a
Because if you have more mass, you have more gravity which increases the amount of energy you produce in your core.
b
Because if you have more mass, you must have a bigger radius to keep your surface so hot.
c
Because if you have more mass, you have to have more temperature to keep your surface blue.
d
Because if you have more mass, you have to have more luminosity to keep your temperature so high.