Which of the following examples illustrates an energy transfer between the atmosphere and hydrosphere?
a plant roots absorbing water from the soil
b polar ice reflecting the sun's light back toward space
c convection currents in the ocean mixing warmer and cooler water together
d loss of heat from a geothermal vent to the surrounding cooler water

b).  polar ice reflecting the Sun's light back toward space

Explanation:

When polar ice reflect the light incident from Sun then the Ice will absorb some of its energy and the remaining energy is reflected back.

Due to this the smaller amount of energy which is reflected back is of higher wavelength as we know that

Now this higher order wavelength is absorbed by the gases present in the atmosphere like Carbon-dioxide and other.

So this is the transfer of energy from hydrosphere to atmosphere.

so here correct answer will be

b). polar ice reflecting the Sun's light back toward space

c)as speed changes, wavelength and frequency change.

everything changes!