Why do the gas giants have many moons?

Which of the following is a true statement? a. individuals evolve to have adaptations. b. individuals have adaptations that can change over time. c. individuals have traits that may or may not make them successful at reproduction. d. populations cant evolve, only individual organisms.

What organs comprise the respiratory system of a bird

How do all types of diffusion/passive transport actually ‘work’ without using even the smallest amount of cellular energy?