According to paragraph 3, why must organisms compromise between competing demands? A. Aparticular organ or structure may be unable to respond to selection pressures due to the needs of other parts of the organism. B. An organism's ability to respond to the forces of selection depends on the demands of other organisms within its environment. C. An organism's environment and its genotype try at the same time to influence its ability to respond to natural selection. D. Different elements of the environment call for adaptations that are often incompatible with one another