As part of review of systems, a 55 year-old male describes an inability to achieve erection. The patient has mild diabetes and is on an ACE inhibitor for hypertension. Which of the following is the most appropriate first step in evaluation? 1-Penile Doppler ultrasound 2- Serum gonadotropin level 3- Information about libido and morning erections 4- Therapeutic trial of sildenafil 5- Nocturnal penile tumescence testing From: Pre Test Medicine 12th