Amongst the following methods of contraception,which can be regarded as the most cost-effective and easily reversible method of contraception?

$IUDs$ within .......... of coitus have been found to be very effective as emergency contraceptives as they could be used to avoid possible pregnancy due to rape or casual unprotected intercourse. (in $hours$)

Match the following columns:

Column-$I$	Column-$II$
$(A)$ Barrier	$(1)$ Copper-$T$
$(B)$ $IUD$	$(2)$ Vasectomy and tubectomy
$(C)$ Surgical technique	$(3)$ Condoms,cervical caps
$(D)$ Administering hormones	$(4)$ Oral pills and Saheli

One of the following is not a method of contraception. Which one?

What is the significance of the progesterone-estrogen combination as a contraceptive measure?

In females,the oviducts are surgically cut or tied to prevent fertilization. This procedure is called: