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: Biochemistry
Haemoglobin unlike myoglobin shows - 
Select and explain. 
A. Parabolic curve of oxygen association, B. Co-operative effect of combine O2, C. Co-operative index of 81, D. Hill's coefficient of 1
B: Co-operative effect of combine O2
Answer: B: Co-operative effect of combine O2 
Explanation: Hemoglobin shows Co-operative binding kinetics i.e. binding of one O2 facilitates binding of other O2 molecules.
Hb-O2 dissociation curve is sigmoid (not parabolic).
Hill coefficient for hemoglobin is 2.8, whereas it is 1 for myoglobin.
There is no term like cooperative index.