Interstellar space (the space between the stars) is filled with extremely low-density hydrogen gas. In the vicinity of a hot star, this gas can be heated to a very high temperature. This hot, low-density gas will:

a. emit light at all wavelengths, in a blackbody spectrum characteristic of a hot gas.

b. reflect light at specific wavelengths characteristic of hydrogen.

c. emit light at specific wavelengths characteristic of hydrogen.

d. emit light at all wavelengths.

c. emit light at specific wavelengths characteristic of hydrogen.

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.

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