The third and last option is correct.
Species in the past (referring to dinosaurs) were more massive.
levels where higher in the past, which meant that plants prospered during that time since they had a easy access to food. That contributes to the fact that herbivores could grow bigger because there was more food. Which in turn, increases the size of early carnivores which eat bigger herbivores.
Hope it helped,
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I'm pretty sure it's deposition because the sediments in the water(soil) are building up on the rock.
The survival of the 2 percent of the population is due to the presence of a gene obtained from other species. This gene must be responsible for developing resistance in the insects, against the insecticide that was used by the farmer. The gene got incorporated in only 2% of the insects and therefore, they survived and rest of them were susceptible to the insecticide and thus, died.