Question

a large celestial body made of gases that emits light due to nuclear reactions is called- a nebula a comet a galaxy a star

Explanation:

A star is a large celestial body composed mainly of gases (like hydrogen and helium). It emits light and heat due to nuclear fusion reactions (like hydrogen - to - helium fusion) occurring in its core. A nebula is a cloud of gas and dust in space. A comet is a small celestial body made of ice, dust, and rocky material. A galaxy is a large collection of stars, gas, dust, and dark matter.

Answer:

a star