The client is scheduled for a Tensilon test to check for Myasthenia Gravis. Which medication should be kept available during the test?

During a Tensilon test to check for Myasthenia Gravis, Atropine sulfate should be kept available as it is the antidote for Tensilon and is administered to manage cholinergic crises that may occur during the test. Atropine sulfate helps counteract the excessive stimulation of the parasympathetic nervous system caused by Tensilon. Furosemide (choice B) is a diuretic and not related to managing Tensilon-induced crises. Prostigmin (choice C) is used to treat Myasthenia Gravis itself, not for managing the effects of Tensilon. Promethazine (choice D) is an antiemetic and antianxiety agent, which is not necessary for a Tensilon test. Therefore, Atropine sulfate (choice A) is the correct medication to have available during a Tensilon test, making choices B, C, and D incorrect in this context.