Select the mismatch w.r.t function of contraceptives.

Answer

To solve the question regarding the mismatch with respect to the function of contraceptives, we will analyze each option provided:

1. **Oral contraceptive pills prevent ovulation.**
- Oral contraceptive pills (OCPs) are designed to prevent ovulation by releasing hormones that inhibit the release of eggs from the ovaries. This statement is correct.

2. **Barrier method prevents lactation.**
- The barrier method of contraception (such as condoms, diaphragms, etc.) works by physically blocking sperm from reaching the egg, thus preventing fertilization. It does not have any role in preventing lactation. This statement is incorrect.

3. **Vasectomy prevents gamete transport.**
- Vasectomy is a surgical procedure for male sterilization that involves cutting or blocking the vas deferens, which prevents sperm from being included in the ejaculate. This statement is correct.

From the analysis above, the mismatch is clearly identified. The correct answer to the question is:

**Barrier method prevents lactation** (This is the incorrect statement).

### Step-by-Step Solution:
1. **Identify the functions of each contraceptive method.**
- Oral contraceptive pills prevent ovulation.
- Barrier methods prevent fertilization.
- Vasectomy prevents gamete transport.

2. **Evaluate each statement for correctness.**
- Confirm that oral contraceptive pills indeed prevent ovulation (correct).
- Confirm that barrier methods prevent fertilization, not lactation (incorrect).
- Confirm that vasectomy prevents gamete transport (correct).

3. **Determine the mismatch.**
- The statement about barrier methods preventing lactation is the only incorrect statement.

4. **Conclude with the correct answer.**
- The mismatch with respect to the function of contraceptives is: **Barrier method prevents lactation**.