Final answer:
The diagnosis of acute cholecystitis would be confirmed by a right upper quadrant abdominal ultrasound.
Step-by-step explanation:
The correct answer is c) Right upper quadrant abdominal ultrasound. Acute cholecystitis is inflammation of the gallbladder, typically caused by gallstones. It is commonly characterized by the triad of fever, abdominal pain, and vomiting. To confirm the diagnosis of acute cholecystitis, a right upper quadrant abdominal ultrasound is performed.