The correct answer is Option (4) – To increase population size.
The reason "To increase population size" is not a valid purpose for the use of contraceptive methods.
Contraceptive methods are used primarily to prevent unwanted pregnancies, control birth rates, and reduce the occurrence of unsafe abortions by allowing individuals to plan and space their pregnancies according to their preferences and circumstances. Contraceptives help individuals and couples make informed choices about family planning and avoid pregnancies when they are not desired.
However, the use of contraceptives is not intended to increase population size. On the contrary, the use of contraceptives often aligns with efforts to manage population growth by enabling individuals to have the number of children they desire while preventing unintended pregnancies. Therefore, increasing population size is not a reason for the use of contraceptive methods.