Pathology Factor Xa is necessary for conversion of prothrombin to thrombin A Only in the extrinsic pathway B Only in the intrinsic pathway C As part of both extrinsic and intrinsic pathways D Only if the normal blood clotting cascade is inhibited 💡 Explanation Factor Xa is necessary for conversion of prothrombin to thrombin ✓ Correct Answer: C. As part of both extrinsic and intrinsic pathways