Definition of Drug: The drug in question is an immunosuppressant used to prevent organ rejection in transplant patients by suppressing the immune system.
Option Analysis:
(1) Cyclosporin-A, Trichoderma polysporum: Cyclosporin-A is a well-known immunosuppressant derived from the fungus Trichoderma polysporum. This is correct.
(2) Stain, Trichoderma polysporum: "Stain" is not a recognized drug for organ transplants, and while Trichoderma polysporum produces Cyclosporin-A, "Stain" is irrelevant. This is incorrect.
(3) Cyclosporin-A, Monascus purpureus: Monascus purpureus is a fungus used to produce red yeast rice and food colorants, not Cyclosporin-A. This is incorrect.
(4) Stain, Monascus purpureus: Neither "Stain" nor Monascus purpureus is associated with an immunosuppressant drug for transplants. This is incorrect.
Mechanism Insight: Cyclosporin-A works by inhibiting T-cell activation, crucial for preventing rejection of transplanted organs.
Conclusion: The correct answer is (1) Cyclosporin-A, Trichoderma polysporum, as it accurately identifies the drug and its fungal source.