Regarding Laboratory Testing to Detect Known Causes of Thrombosis

Regarding laboratory testing to detect known causes of thrombosis:

A) Testing is best performed as soon as possible after the thrombosis is diagnosed, but before the patient receives anticoagulants.
B) It is best to test using plasma drawn after the patient has begun anticoagulant therapy, so the effects of the thrombus are masked.
C) Testing during the acute thrombotic event can result in false positives and false negatives
D) Genetically based tests, such as those for MTHFR, prothrombin G20210A, and factor V Leiden, are affected by anticoagulant therapy and the presence of thrombus.
E) It is acceptable to test for inherited causes of thrombophilia during the acute event, but not for acquired causes.