The rejection of organ transplanting in humans is prevented by using:

Options

A. Aspirin
B. thrombin
C. calcitonin
D. cyclosporine

Answer

**Step-by-Step Solution:**

1. **Understanding Organ Transplant Rejection**: When an organ is transplanted into a recipient, the recipient's immune system may recognize the new organ as foreign and attack it. This is known as organ transplant rejection.

2. **Role of Immunosuppressive Drugs**: To prevent this rejection, immunosuppressive drugs are used. These drugs help to suppress the immune response, allowing the body to accept the transplanted organ.

3. **Identifying the Correct Drug**: Among the options provided:
- Aspirin is primarily used as a pain reliever and anti-inflammatory.
- Thrombin is involved in blood clotting.
- Calcitonin is involved in calcium regulation in the body.
- Cyclosporine is an immunosuppressive drug specifically used to prevent organ rejection.

4. **Conclusion**: The correct answer is cyclosporine, as it is the drug that effectively prevents the rejection of transplanted organs by suppressing the immune response.

**Final Answer**: The rejection of organ transplanting in humans is prevented by using cyclosporine.

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