Question

1. what factor determines the path a star will take in its post - main sequence?

amount of light
gravitational pull
number of hydrogen molecules
mass

Explanation:

The mass of a star is the key factor. After the main - sequence stage, a star's mass determines whether it will become a white dwarf (low - mass stars), a neutron star (intermediate - mass stars), or a black hole (high - mass stars). The amount of light is related to luminosity which is influenced by mass but not the determining factor. Gravitational pull is related to mass. The number of hydrogen molecules is not the direct determining factor as it's the mass (which includes all elements, not just hydrogen) that matters in the post - main sequence evolution.

Answer:

mass