In this question, we are asked to pick the incorrect pair from the given options.
Step 1: Let's analyze each pair:
- Natural method - Lactational amenorrhea: This is a correct pair. Lactational amenorrhea is a natural method of contraception that occurs due to the hormonal changes after childbirth.
- Barrier - Vault: This is also a correct pair. The vault refers to a type of barrier method for contraception.
- Contraceptive pill - Saheli: This is a correct pair. Saheli is an oral contraceptive pill.
- Intra uterine device - Cervical cap: This is the incorrect pair. Intra uterine devices (IUDs) and cervical caps are two different types of contraception. The IUD is inserted into the uterus, whereas a cervical cap is placed over the cervix.
Step 2: Based on this, the incorrect pair is option (4).