What is the main purpose of the light-dependent reactions

The main purpose is to energize electrons! These reactions energize electrons so that they can move through a chain of proteins in the internal chloroplasts membranes.

as the gila monster consumes the eggs or young of the desert cottontail and gambel's quail, thus its main food supply is only accessible for a restricted time duration every year. however, for this, the gila monsters exhibit three adaptations, which elevate their survival rate in the desert condition.  

first, is that they possess huge bodies, and can consume greater concentrations of food during a small period. secondly, they require to feed infrequently as they can accumulate fat in their tails. ultimately, their rate of metabolism is very low, so that they can burn their reservoirs of fat gradually.  

it is either c or d and i know for sure it is not a or b