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
Characteristic CT finding in acute SDH is- 
Select and explain. 
A. Crescent shaped hyperdense lesion, B. Biconvex hyperdense lesion, C. Biconcave hyperdense lesion, D. Crescent shaped hypodense lesion
A: Crescent shaped hyperdense lesion
Answer: A: Crescent shaped hyperdense lesion 
Explanation: Ans. is 'a' i.e. Crescent shaped hyperdense lesion Appearance of hematomas on CT* Biconvex (lens shaped or lenticular) hyperdense(2/3rd) or mixed density lesion(l/3rd) - Epidural hematoma.* Crescent (concao-convex) hyperdense (<2 weeks) or isodense (2-4 weeks) or hypodense (>4 weeks) lesion - subdural hematoma.