Which statement made by a client taking nitroglycerin as needed (prn) indicates understanding of the instructions for safe use of this drug?

"l discard unused pills after six months after replacing it with a new vial."

“I won’t take this medication if I have a headache because it Will make it worse."

“I will remain flat in bed for one hour after I take this medication,"

“I will go to the emergency room if I develop a tingling feeling on my tongue.”