The correct answer is: B. Eastward from the first point of Aries.
Right ascension (RA) is the angular distance measured eastward along the celestial equator from the vernal equinox to the hour circle of a celestial object. It is one of the two coordinates of the equatorial coordinate system, the other being declination.
The vernal equinox is the point on the celestial sphere where the Sun crosses the equator from south to north in the spring. It is also the first point of Aries, the first sign of the zodiac.
The hour circle of a celestial object is the great circle on the celestial sphere that passes through the object and the celestial poles.
The right ascension of a celestial object is measured in hours, minutes, and seconds of time. It is positive for objects east of the vernal equinox and negative for objects west of the vernal equinox.
The right ascension of a celestial object is important because it is used to determine the time at which the object will rise and set. It is also used to determine the position of the object in the sky.
The other options are incorrect because they measure right ascension in the wrong direction.