endothelial is the ans dud
theories are ideas of why something happens. They are not considered "true" unless backed up with a series of scientific studies. Then it would be more of a law.
Variation: people in the population need to have different traits.
Heritability: the different traits need to be able to pass from parent to offspring.
Differential Mortality: people need to have the probability of survival that is a function of the trait in question.
Answer:
They are herbivores and eat marine algae growing along rocky shores and underwater. In the water, they swim with a snake-like motion and hold themselves against the bottom with their long claws in order to graze. Though they feed in the water, marine iguanas are predominately terrestrial.
