What does the term solstice mean?

a) longest day of the year

b) shortest day of the year

c) equal day and night

d) both a and b 

The term solstice means both longest, as well as shortest days of the year. It happens twice every year. Summer solstice is the longest day of the year, which is 21st June and the winter solstice is the shortest day of the year on December 22. Do you know the meaning of equinox?.