If the maternal mortality rate (MMR) and infant mortality rate (IMR)…

The correct answer is Option (3) → Population will increase.

Population size depends on how many people are born and how many die. MMR (maternal mortality rate) is the death rate of mothers linked to pregnancy and childbirth. IMR (infant mortality rate) is the death rate of babies in their first year. When these death rates fall, more mothers and babies survive, while births go on as before.

Option (1) No change in the growth rate. — Incorrect. If fewer mothers and infants die and births stay the same, the gap between births and deaths widens. So the growth rate does change; it goes up.

Option (2) A decline in the growth rate. — Incorrect. A fall in deaths cannot slow growth. Growth slows only when births fall or deaths rise.

Option (3) Population will increase. — Correct. The book lists the rapid decline in death rate, MMR and IMR as a main reason for the steep rise in India’s population, which crossed 1.2 billion in 2011.

NCERT Extract:
Population Stabilisation and Birth Control – “… Our population which was approximately 350 million at the time of our independence reached close to the billion mark by 2000 and crossed 1.2 billion in May 2011. A rapid decline in death rate, maternal mortality rate (MMR) and infant mortality rate (IMR) as well as an increase in number of people in reproducible age are probable reasons for this.”