After population growth, what does the united nations believe will be the greatest future global problem?
a.
lack of usable freshwater
b.
lack of arable land
c.
excessive levels of air pollution
d.
excessive water pollution

The answer is letter A) the lack of usable fresh water. Fresh water is very useful for us and to our growing population. It helps generate food, especially in the farming sector where plants rely on water and sun to thrive. If water starts to be scarce, draughts and famines are most likely to occur