Action of vaginal diaphragm is

The correct option is "prevent the sperm to come in contact with ova".

Step-by-Step Explanation:

1. Understanding the Vaginal Diaphragm:
A vaginal diaphragm is a barrier method of contraception. It is a reusable, dome-shaped silicone or latex cup with a flexible rim. It is inserted into the vagina prior to sexual intercourse and positioned to cover the cervix (the opening to the uterus).

2. Mechanism of Action:
The primary function of the diaphragm is to act as a physical barrier. By covering the cervix, it physically blocks the path of semen. This prevents sperm from entering the uterine cavity and traveling up the fallopian tubes.

3. Preventing Fertilization:
Since the sperm are physically blocked from entering the uterus, they cannot reach the fallopian tubes where fertilization usually occurs. Consequently, the sperm are prevented from coming into contact with the ovum (egg), preventing fertilization and conception.

4. Distinguishing from other options:
- Anti-implantational: Methods like intrauterine devices (IUDs) or emergency contraceptive pills may work by preventing a fertilized egg from implanting in the uterine wall. The diaphragm stops fertilization itself, not implantation.
- Spermicidal: While diaphragms are often used in combination with spermicidal jellies to increase efficacy, the diaphragm itself is a physical barrier, not a chemical spermicide.
- Prevent the ova to come in the uterus: The diaphragm does not affect the release of the ovum from the ovaries or its passage through the fallopian tubes into the uterus; it only blocks the sperm from moving upward.