The correct answer is A) 0° declination going to southerly declinations. The autumnal equinox occurs when the Sun's declination is 0°, meaning it is directly over the Earth's equator. At this point, the Sun is transitioning from northerly declinations to southerly declinations as it appears to move southward in the sky. The other options are incorrect because B) and D) refer to the maximum northern and southern declinations of the Sun, which occur at the solstices, not the equinoxes. Option C) is incorrect because it describes the vernal equinox, not the autumnal equinox.