which of the following is true?

a. the poles receive the highest amount of insolation.
b. the highest levels of insolation occur in the equatorial and tropical latitudes.
c. insolation is equal at all surfaces across the globe.
d. there is always a very predictable latitudinal gradient of insolation.

b. The highest levels of insolation occur in the equatorial and tropical latitudes.

Explanation:

As we know insolation  is zero at the poles and maximum at the equator. It decreases from the equator to poles. B is the right option.The sun is closest to the earth in January (winter in the northern hemisphere), so that the maximum solar insolation received in the southern hemisphere is greater than that received in the northern hemisphere. At the equinoxes, solar insolation is at a maximum at the equator and is zero at the poles.

not only is it colder, it also becomes darker, less salty, and more dense.