Exponential phase of human growth started about

$A$ : Every sixth person in the world is an Indian.
$R $: Life expectancy depends upon average life span

According to $1991$ census, the number of females per $1000$ males is

The latest technique to produce a child is $GIFT$. The full form is

$A$ : Inability to conceive or produce children even after $2 \;years$ of unprotected sexual cohabitation is infertility.
$R$ : In vitro fertilization followed by transfer of embryo into the female genital tract is ‘Test Tube Baby’ programme