The table below gives life history characteristics of an endangered grassland bird in two geographically distinct populations. Assume that the species follows a logistic growth model. Calculate the population growth rate (dN/dt) for both populations.
Population | No. of individuals (N) | Births/year (B) | Deaths/year (D) | Carrying capacity (K)
Rajasthan (R) | 120 | 42 | 6 | 240
Maharashtra (M) | 300 | 96 | 6 | 375
Based on this data, which one of the following options gives the combination of correct inferences about the growth rate in both populations?

Correct option is C

Correct Answer:
(c) Both populations are growing AND (dN/dt)_R = (dN/dt)_M
Explanation:
For logistic growth,
dN/dt = (B − D) (1 − N/K)
Rajasthan (R):
B − D = 42 − 6 = 36
1 − (120 / 240) = 1 − 0.5 = 0.5
dN/dt = 36 × 0.5 = 18
Maharashtra (M):
B − D = 96 − 6 = 90
1 − (300 / 375) = 1 − 0.8 = 0.2
dN/dt = 90 × 0.2 = 18
Inference:
Growth rate is positive in both populations → both are growing
Growth rates are equal in both populations
Hence, option (c) is correct.