Which of the following BEST describes what occurs in a fusion reaction?

a
Two low mass nuclei are joined to form one nucleus and gives off energy.

b
Electrons are shared between the nuclei.

c
A single nucleus divides into two or more nuclei and gives off energy.
d
A chemical reaction occurs between the nuclei.

The correct answer is:

a
Two low mass nuclei are joined to form one nucleus and gives off energy.