Why are there so many varied phenotypes within a species such as humans?

Which of the following describes a boom period? a. as one population increases, another population decreases. b. as one population increases, the other population also increases. c. as one population decreases, another population increases. d. as one population decreases, another population also decreases

How do living things obtain phosphorus

Why did adult crab numbers decline in he ecosystem, even though sea stars were still available?