Air is warmer and less dense than surrounding air at the equator because the equator receives more?
a: wind
b: air pressure
c: solar energy
d: greenhouse gases

Solar energy

Given the fact that near the equator you have the sun at roughly the same level all year, you deal with very little to no temperature change, whereas North or South of the equator experiences temperature change due to increasing or decreasing distance from the sun when the earth tilts on its axis.

It maybe because uranus is made of gas but uranus has a solid core in the middle