This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Physiology
Cardiac index is defined as: 
Select and explain. 
A. Stroke volume M2/BSA, B. C.O.P. per unit body surface area, C. Syst press/M2 BSA, D. End diastolic volume
B: C.O.P. per unit body surface area
Answer: B: C.O.P. per unit body surface area 
Explanation: B i.e. COP per unit body surface area