Which one of the following human organs is often called the "graveyard" of $RBCs$?

$A$ person with blood group $A$ can receive blood from which of the following groups?

What is the average lifespan of blood platelets?

The iron-free compound of haemoglobin is:

The function of vitamin $K$ is:

Factors for coagulation or clotting of blood are present in the plasma in an .......... form and plasma without clotting factor is called ........