The tiny hummingbird weighs little, but its egg is 15 percent of the adult hummingbird' s weight. The volume and weight of an adult goose are much greater than those of a hummingbird, but a goose' s egg is only about 4 percent of its own weight. An adult ostrich, much larger and heavier than a goose, lays an egg that is only 1. 6 percent of its own weight. Which one of the following propositions is best illustrated by the statements above? ['The eggs of different bird species vary widely in their ratio of volume to weight.', 'The smaller and lighter the average adult members of a bird species are, the larger and heavier the eggs of that species are.', 'The ratio of egg weight of a species to body weight of an adult member of that species is smaller for larger birds than for smaller ones.', "The size of birds' eggs varies greatly from species to species but has little effect on the volume and weight of the adult bird."]