Answer:
C) plasma
A star is a luminous ball of hot plasma held together by its own gravity.
Step-by-step explanation:
Stars are formed from molecular clouds. When a cloud receives an impact wave from a near supernova or another astronomical event, as a consequence, it will start to collapse under its gravity, until it breaks in small pieces (each of this pieces will become a star).
Stars are submitted to a hydrostatic equilibrium (its gravitational force pulls inward and its nuclear pressure pulls outward), that gave rise to higher pressures and higher temperatures, those temperatures allow atoms being completely ionized¹. Stars are compounded with a gas mixture of atoms, free protons and free electrons (plasma).
¹Ionized: When an atom loses electrons.