The correct statement about natural selection is:
c) The fittest organisms are better able to survive and reproduce in an environment.
This statement reflects the essence of natural selection, where "fitness" is defined by an organism's ability to survive and reproduce in its specific environment.
Let's briefly evaluate the other statements:
a) A stable environment helps shift a population’s genetic variance toward a new trait. — This is incorrect; a stable environment is more likely to maintain existing traits rather than shift genetic variance toward a new trait.
b) Traits that negatively affect survival are more likely to be common in the population. — This is incorrect; traits that negatively affect survival are typically selected against and would be less common over time.
d) Populations tend to produce fewer individuals than the environment can support. — This is misleading; typically, populations produce more offspring than the environment can support, leading to competition for resources.
Thus, the best answer is c.