During a(n) the sun's energy hits the earth's hemispheres the most evenly, and during a(n) it hits the earth's hemispheres the most unevenly. a. equinox . . revolution b. equinox . . solstice c. solstice . . rotation d. solstice . . equinox

The correct option is B.
Equinox refers to the period of the year when the sun crosses the equator and day and night are of equal length. Usually occur at September 22 of each year. 
Solstice refers to the period of the year when the sun is at its highest or lowest point in the sky at noon. During this period, there is variation in the duration of the night and the day.