What do 'a' and 'b' represent in the following population growth curve?

'a' represents exponential growth when responses are not limiting the growth; and 'b' represents logistic growth when responses are limiting the growth.

'a' represents logistic growth when responses are not limiting the growth; 'b' represents exponential growth when responses are limiting the growth.

'a' represents carrying capacity and 'b' shows logistic growth when responses are limiting the growth.

'a' represents exponential growth when responses are not limiting the growth and 'b' shows carrying capacity.