In an Economy with Population Growth at Rate N, the Change

In an economy with population growth at rate n, the change in capital stock per worker is given by the equation:

A) ∆k = sf(k) + δk.
B) ∆k = sf(k) - δk.
C) ∆k = sf(k) + (δ + n) k.
D) ∆k = sf(k) - (δ + n) k.