Why is it difficult to breathe at high altitudes?

Which conditions are necessary for natural selection to occur? select all of the answers that apply. a. inheritable adaptations vary among individuals. b. the population size is increasing. c. more individuals are born than can survive. d. fitness varies among individuals. e. the environment changes suddenly and drastically.

Akrabby blind whale has married pearl who has normal vision. oneof their two sons is also colorblind. what arr the genotypes of the parents?

What best describes the structure of the declaration of independence?