NBME form 2 - Taking Consent before pelvic examination

A 15-year-old girl is brought to the emergency department by her 20-year-old sister because of a 1-week history of fatigue, nausea, and abdominal pain. Menarche was at the age of 12 years, and her last menstrual period was 3 weeks ago. She has not had vaginal discharge. She is sexually active, and she and her partner use condoms inconsistently. Her temperature is 37 C (98.6 F), blood pressure is 110/60 mm Hg, and pulse is 95/min. Abdominal examination shows mild bilateral lower quadrant tenderness. Before a pelvic examination and a pregnancy test can be performed in this patient, consent must be obtained from which of the following?

A) The court

B) The patient

C) The patient's parent

D) The patient's sister

E) No consent is necessary

Please explain you answer. Thanks.