Number of births per thousand people in the population is expressed as

Population explosion is:

Which one of the following factors has contributed most to the rapid rise of the human population in the present century?

What is the main cause of population explosion in India?

Population explosion occurs due to

Statement $1$: Human population doubles after every $35 \; \text{years}$ as against $200 \; \text{years}$ in $1600-1800$.
Statement $2$: Rapid increase is due to better health facilities.