Why Does Total Fertility Rather Than the Actual Birth Rate

Why does total fertility rather than the actual birth rate give a more accurate picture of a population's potential to grow?

A) Because total fertility tells you how many children women have overall
B) Because total fertility tells you how many children women actually have on average
C) Because birth rate tells you how many children women are actually having which can change as society changes
D) Because total fertility tells you how many children women could have rather than how many they do have, so it is higher than birth rate
E) Because birth rate changes over time and total fertility is constant