The right ascension is the equivalent of longitude on the celestial sphere, and it is given in the units of

The correct answer is: B. time-hours, minutes and seconds.

Right ascension is a coordinate that specifies the position of an object on the celestial sphere in the equatorial coordinate system. It is the equivalent of longitude on Earth. Right ascension is measured in hours, minutes, and seconds, east of the vernal equinox. The vernal equinox is the point on the celestial sphere where the Sun crosses the equator from south to north in the spring.

The other options are incorrect. Option A is incorrect because right ascension is not measured in degrees. Option C is incorrect because right ascension is measured in hours, minutes, and seconds, not just hours. Option D is incorrect because right ascension is not measured in seconds only.