A medical assistant administers a scratch test to a patient who has a history of mild environmental allergies. To ensure a reliable test outcome, the medical assistant should compare the test site reactions primarily to which of the following?
Previous scratch test results, assuming the patient's condition has remained unchanged since the last test.
A clear test area located far from the allergen application sites to evaluate baseline skin conditions.
The histamine control, which provides a positive benchmark indicating an allergic reaction.
The area with the most intense reaction regardless of the substance applied, to determine the highest sensitivity.