Population surge $230$ years ago was due to
Industrial revolution
Agricultural revolution
Cultural revolution
Intellectual revolution
The animal population becomes too large for its feeding source or its habitat, its members starve die but humans escape this disaster by
Castration cannot be taken as a contraceptive device, because
Which of the following cannot protect the user from contracting $AIDS$?
Developing country having high death rate is
According to $1991$ census, the number of females per $1000$ males is