Can someone help me this is for astronomy but there’s no option stars produce large amounts of energy by the process of ?

the options are
A. gravity
B. nuclear fusion
C. luminosity
D. friction

This is what i found on google “phytoplankton, tiny organisms that live in the ocean, are autotrophs. some types of bacteria are autotrophs. most autotrophs use a process called photosynthesis to make their food.” i hope this you for what your looking for

A) early horses is your answer