The protein which prevents coagulation of blood in the blood vessel is

Continuous bleeding from an injured part is due to the deficiency of $..........$.

$RBCs$ have an average life span of (in $days$)

Which of the following blood corpuscles are least in number,in human beings?

Study the diagram given below and identify the cells labelled as $A$, $B$, $C$ and $D$, and choose the correct option.

$A$ certain road accident patient with unknown blood group needs immediate blood transfusion. His one doctor friend at once offers his blood. What was the blood group of the donor?