In some tribes,the population does not grow appreciably because of

Asymptote in a logistic growth curve is obtained when

In the exponential growth equation $N_{t}=N_{0} e^{rt}$,$e$ represents :

Which one is correct for the logistic model of population growth?
$I.$ Population growth rate increases as the size of the population approaches the carrying capacity.
$II.$ All individuals have the same effect on population growth.
$III.$ There are unlimited natural resources.
$IV.$ As population increases,the competition goes on increasing.
Select the correct combination.

The present population of the world is about

The asymptote stage of a population is the stage in which the population is: