This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Gastrointestinal Radiology, Subject name: Radiology
A 43 - year - old lady presents with colicky right upper quadrant pain which radiates to right shoulder and is exacerbated by eating fatty foods. Which of the following radiological investigations should you request first ? 
Select and explain. 
A. Abdominal ultrasound, B. Abdominal CT, C. Abdominal X - ray, D. Magnetic resonance cholangiopancreatography
A: Abdominal ultrasound
Answer: A: Abdominal ultrasound 
Explanation: Clinical presentation is suggestive of Gall stones. 1st investigation to be performed is abdominal ultrasound, as most of the gall stones are radiolucent.