a gene a protein a platelet a DNA molecule
I gave my students this multiple choice question: Tissue plasminogen activator is a natural blood thinner. The coded sequence for the blood thinner is called PLAT , found on chromosome 8. It is used to treat people who have heart attacks and strokes. Tissue plasminogen activator can be made through genetic engineering. What is tissue plasminogen activator?

Only one answer is correct among these 4 choices:
- a gene
- a protein
- a platelet
- a DNA molecule

Could you tell me which one is correct?

a protein