Biology 8th Edition by Kenneth Mason ,Jonathan Losos,Susan Singer,Peter Raven,George Johnson

Exercise 6

When the environment changes from year to year and different phenotypes have different fitness in different environments
A) natural selection will operate in a frequency-dependent manner.
B) the effect of natural selection may oscillate from year to year, favoring alternative phenotypes in different years.
C) Genetic variation is not required to get evolutionary change by natural selection.
D)none of the above.