I. High birth rate and high immigration rate

II. Low birth rate and high immigration rate

III. Low mortality rate and low emigration rate

IV. High mortality rate and high emigration rate.

Which combination of the above can cause rapid over-crowding in climax biotic communities and human settlements? 

A.

II and III

B.

I and III

C.

I and IV

D.

I and II

Correct answer is B

Low mortality rate, high birth rate, high immigration rate and low emigration rate are causes for rapid overcrowding.