Which one of the following statement is correct with respect to immunity

Options

A. Perfoemed antibodies need to be injected to treat the bite by a viper snake.
B. The antibodies against smallpox pathogen are produced by T-lymphocytes.
C. Antibodies are protein molecules, each of which has for light chains.
D. Rejection of a kindeny graft is the function of B-lymphocytes.

Answer

To determine which statement is correct with respect to immunity, we will analyze each option provided in the question.

### Step-by-Step Solution:

1. **Analyze Option A**: "Preformed antibodies need to be injected to treat the bite by a viper snake."
- When a person is bitten by a venomous snake, they can be treated with antivenom, which contains preformed antibodies that neutralize the venom. Therefore, this statement is **correct**.

2. **Analyze Option B**: "The antibodies against smallpox pathogen are produced by T lymphocytes."
- This statement is incorrect because antibodies are produced by B lymphocytes, not T lymphocytes. T lymphocytes are involved in cell-mediated immunity, while B lymphocytes are responsible for humoral immunity (producing antibodies).

3. **Analyze Option C**: "Antibodies are protein molecules, each of which has a light chain."
- This statement is misleading. Antibodies are indeed protein molecules, but they consist of two heavy chains and two light chains. Therefore, this statement is **incorrect**.

4. **Analyze Option D**: "Rejection of a kidney graft is the function of B lymphocytes."
- The rejection of a kidney graft is primarily mediated by T lymphocytes, not B lymphocytes. T lymphocytes recognize foreign tissues and initiate the rejection process. Thus, this statement is also **incorrect**.

### Conclusion:
After analyzing all the options, the only correct statement is **Option A**: "Preformed antibodies need to be injected to treat the bite by a viper snake."

---