Solar energy and possibly electricity
The correct option is A.
Fitness refers to the quantitative representation of natural and sexual selection within an evolution. Fitness can be defined in respect to a genotype or a phenotype. Relative fitness is described as the survival or reproductive rate of a genotype or phenotype relative to maximum survival or reproductive rate of other genotypes in the population. Thus, the fitness of a population can be determined by finding out the number of offspring that survive to adulthood.
During Digestion the "food" becomes something called Chyme. Its a semi-solid substance and then the leftovers that aren't used turn into feces. <span />
I think D is the right answer.
