Stellar evolution is the process of planetary formation the life cycle of a star the death of a star how comets form

B.) Stellar evolution is "the life cycle of a star"

Hope this helps!

The life cycle of a star.
Planetary formation has nothing to do with the word stellar
The death of a star is only one phase in it's evolution
How comets form is a branch of planetary, as comets are actually speeding asteroids, or so I've heard :)

Ithink d is the right answer. hope this !