Final answer:
The mass of a star directly determines how much fuel it has and affects its temperature, pressure, fusion rate, and lifetime.
Step-by-step explanation:
The mass of a star directly determines how much fuel it has. Mass determines the star's temperature and pressure in its core, which in turn affects the rate of fusion and the star's lifetime. Massive stars have more fuel but burn it faster, leading to shorter lifetimes compared to low-mass stars.