Periodic abstinence is an example of:

The correct answer is Option (4) → Natural method of contraception

Option (4) Natural method of contraception — Correct. Periodic abstinence uses no device, drug or surgery; the couple only avoids coitus in the fertile period. So it is a natural method, not a hormonal, barrier or surgical one.

NCERT Extract:
Population Stabilisation and Birth Control – “… Natural methods work on the principle of avoiding chances of ovum and sperms meeting. Periodic abstinence is one such method in which the couples avoid or abstain from coitus from day 10 to 17 of the menstrual cycle when ovulation could be expected. As chances of fertilisation are very high during this period, it is called the fertile period.”