All of the following would result in a change in population size except
a. equal birth and death rates.
b. the death rate exceeding the birth rate.
c. immigration of individuals into the population range.
d. emigration of individuals out of the population range.

The correct answer is letter A.

There will never be an equal birth and death rates within a particular population size. The trend is that one exceeds or is below the other. All of the other choices may affect population size while choice A does not and is highly unlikely to happen.