Assertion (A) : Barrier methods such as condoms prevent the physical meeting of eggs and sperm.

Reason (R) : Condoms are used just before coitus, to prevent the entry of ejaculated semen into the female reproductive tract.

Both A and R are true and R is the correct explanation of A.

The assertion explains that barrier methods, like condoms, are effective in preventing the physical contact between eggs and sperm during sexual intercourse. This is accurate because condoms act as a barrier, physically preventing the sperm from reaching the egg.

The reason provided supports the assertion by explaining how condoms work. It states that condoms are used just before intercourse to stop ejaculated semen from entering the female reproductive tract. This is true because condoms are placed over the erect penis prior to penetration, creating a physical barrier that blocks the passage of sperm into the vagina.