Answer:
c. emit light at specific wavelengths characteristic of hydrogen.
Step-by-step explanation:
The heated hydrogen gas with extremely low density will emit light with specific characteristics of hydrogen wavelengths.
This is because when the gas has a very low density it tends to emit rays of light of a certain frequency. When this gas is close to a star, as shown in the question above, the star promotes a continuous beam of light that accesses the hydrogen gas that absorbs all that energy. In this case, the gas acts as a light source and begins to emit light with specific wavelength characteristics.