In regards to screening tests for preoperative evaluation of bleeding times, which statement is incorrect?

Focusing on the reason why B is marked as incorrect reveals important details about the prothrombin time (PT) test and what factors it assesses. PT primarily measures the extrinsic and common pathways of coagulation, specifically examining factors I (fibrinogen), II (prothrombin), V, VII, and X. The statement in B incorrectly lists the factors involved by omitting factor I (fibrinogen), which is crucial for hemostasis and is measured during the PT.

To provide clarity on the other statements:

The prothrombin time (PT) test, as mentioned, is activated by tissue thromboplastin and serves to evaluate the extrinsic and common pathways, making the first statement true. The activated partial thromboplastin time (APTT) serves to assess the intrinsic and common pathways, and its normal range of 25-35 seconds is widely accepted, confirming the accuracy of the third statement. The international normalized ratio (INR) provides a standardized method for reporting PT, set within the normal range of 0.8-1.2, and is calculated by comparing the patient's PT to a normal PT, validating the correctness of the fourth statement.

Therefore, understanding the specific factors