This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Nervous System, Subject name: Radiology
Investigation of choice for lactating female with a painful lump? 
Select and explain. 
A. USG, B. CT, C. MRI, D. Mammogram
A: USG
Answer: A: USG 
Explanation: Ans. A. USGPainful lump in a lactating female is suggestive of breast abscess. Ultrasound is the investigation of choice for differentiating cystic vs solid swelling.