(A) Lactational amenorrhea: Absence of menstruation during intense breastfeeding. It is a Natural method of contraception. (Correct pair).
(B) Vaults: Rubber caps inserted into the female reproductive tract to cover the cervix. They are Barrier methods. (Correct pair).
(C) Multiload 375: A copper-releasing IUD. It is an Intrauterine Device. (Correct pair).
(D) Saheli: Saheli is a non-steroidal preparation (Centchroman) taken as a pill (once a week). It is an Oral Contraceptive Pill, NOT an implant. Implants are subcutaneous devices containing progesterone/estrogen (e.g., Norplant). (Incorrect/Odd pair).
Step 2: Conclusion:
Option (D) is the odd pair because the classification is wrong.