Question

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

Answer 1

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.

Answer 2

The answer is True :D