A nurse is teaching a patient about the use of sildenafil [Viagra] for erectile dysfunction. Which statement by the patient indicates understanding of the teaching?

"This drug may cause me to have an erection when I don't want one."

"If my erection lasts longer than 6 hours, I should contact my provider."

"If I have chest pain with sildenafil, I can use my nitroglycerin as prescribed."

"I should take this drug 5 minutes before sexual activity."