Final answer:
The diagnostic test that would be within the normal range for an individual with hemophilia A is the Platelet count, as hemophilia A affects clotting factor production, not the number of platelets. The correct option is 3.
Step-by-step explanation:
The diagnostic test that would be within the normal range for an individual with hemophilia A is 3) Platelet count. Hemophilia A is caused by inadequate production of functional factor VIII, which affects the blood\'s ability to clot. However, it does not affect the number of platelets in the blood.
Therefore, a hemophiliac\'s platelet count should be normal. The other tests listed, such as Activated partial thromboplastin time (aPTT), which tests the efficacy of the intrinsic clotting pathway, would be prolonged in hemophilia A due to the lack of factor VIII.
Prothrombin time (PT) tests the extrinsic and common clotting pathways and is not typically affected by hemophilia A. Finally, Fibrinogen level measures the amount of fibrinogen available to be converted into fibrin during clot formation and is generally normal in individuals with hemophilia A.