• Assertion (A) is True: In animal breeding, the rate of inbreeding per generation ($\Delta F$) is inversely proportional to effective population size ($N_e$):

• Reason (R) is True: For a population with unequal numbers of males ($N_m$) and females ($N_f$), the effective population size is given by Sewall Wright's formula:

Because far fewer breeding males (sires) are maintained compared to dams (e.g., in artificial insemination where $N_m \ll N_f$), $N_e$ is almost entirely constrained by the number of the less numerous sex ($N_e \approx 4 N_m$).

• Relationship: (R) is indeed the underlying demographic principle explaining why inbreeding rate is driven by the less numerous sex.

Correct option: (2) Both (A) and (R) are true but (R) is NOT the correct explanation of (A).