(A) : When resources become progressively limiting, the population growth pattern turns logistic.
(R) : Population growth is ultimately limited by the carrying capacity of the environment.
A. If both (A) and (R) are true but (R) is not the correct explanation of (A).
B. If both (A) and (R) are true and (R) is the correct explanation of (A).
C. If (A) is true but (R) is false.
D. If both (A) and (R) are false.