In Which of the Following Ways Does Drug Testing Differ

In which of the following ways does drug testing differ from polygraph testing as part of a hiring process?

A) Drug testing provides less conclusive test results than does polygraph testing.
B) Drug testing is far more controversial as a candidate screen than polygraph testing.
C) Drug testing is far more expensive than polygraph testing because it cannot be done in-house.
D) Drug testing is sometimes mandatory in nongovernmental industries; polygraph testing never is.