The correct options are
C Spring
D Autumn
Equinox is when the position of the Earth is such that the rays of the Sun fall directly on the equator. At this position, the Earth experiences equal days and equal nights because neither of the hemispheres is tilted towards the Sun.
The equinoxes occur in two phases:
1) Autumn equinox- Occurs on 23rd December in the northern hemisphere.
2) Spring equinox- Occurs on 21st March in the northern hemisphere.