The correct answer is D. All of the above.
The First Point of Aries is the point in the celestial sphere where the ecliptic (the apparent path of the Sun across the sky) crosses the celestial equator (the imaginary line in the sky that divides the Northern and Southern Hemispheres). It is usually denoted by the Greek letter $\gamma$. It is located near the very conspicuous rectangle of stars in the constellations of Pegasus and Andromeda.
The First Point of Aries is the origin of celestial coordinates, such as right ascension and declination. It is also the starting point for the zodiac, a belt of 12 constellations that the Sun, Moon, and planets appear to pass through.
The First Point of Aries is not fixed in the sky. It is slowly moving westward due to the precession of the Earth’s axis. This is a slow, cyclical wobble of the Earth’s axis that takes about 26,000 years to complete. As a result, the First Point of Aries will eventually move into the constellation of Pisces.