Answer choices are ..
a ) nuclear fission because an atom splitting into two fragments
b)nuclear fusion because the products that are produced are radioactive
c) nuclear fission because a large amount of energy is being released
d) nuclear fusion because an atomic nuclei combine to form a heavier nucleus

D) nuclear fusion because an atomic nuclei combine to form a heavier nucleus

Explanation:

Nuclear fusion is a process which involves the conversion of two small nuclei to form a heavy nuclei along with release of energy.

Nuclear fission is a process which involves the conversion of a heavier nuclei into two or more small and stable nuclei along with the release of energy.

As in the given reaction a heavier nuclei helium is being formed from combination of deuterium and tritium, this is a nuclear fusion reaction.

i don't see a text, but i am gonna assume this *orbit* the curved path, usually elliptical, described by a planet, satellite, spaceship, etc., around a celestial body, as the sun.