Population momentum refers to situation where :

The correct answer is Option (1) → a large cohort of women of reproductive age will fuel population growth over the next generation, even if each woman has fewer children

Option (1) a large cohort of women of reproductive age will fuel population growth over the next generation, even if each woman has fewer children — Correct. Population momentum means that a population goes on growing because so many women are of reproductive age, even if each of them has fewer children than women of earlier generations. That is why India’s population is projected to rise from 1.2 billion to about 1.6 billion by 2050, although fertility and growth rates are declining.