The number of births and length of life all affect a country’s population and size.
a. true
b. false

Yes, this is true!

The number of births will increase the population in a give place - In fact, that's what lead to the big population of India.

Also the length of life  says something about the death rate; if people live longer, they will die less often (in comparison to the lenght of life) - so longer lenght of life will also mean bigger population.

Ghana, first of the great medieval trading empires of western africa (fl. 7th–13th century). it was situated between the sahara and the headwaters of the sénégal and niger rivers, in an area that now comprises southeastern mauritania and part of mali.