The hottest stars in space are in color.
a. yellow
c. blue
b. red
d. white

The hottest stars are blue

The hottest stars in space are Blue in color.

Explanation:

Hottest stars means very high temperature. From Wein's displacement law, the peak value of surface temperature of a star would be inversely proportional to the peak wavelength the star emits.

High temperature means it would emit small wavelength light. Blue has smallest wavelength in the visible region  which also means large value of frequency -large energy. Thus, a hot star would appear blue in color.

On the other hand, a cool star would have long wavelength which corresponds to red color.