In rabbit,the function of the spleen is

In which of the following aspects does serum differ from blood?

Given below are two statements:
Statement $I$:
The coagulum is formed of a network of threads called thrombins.
Statement $II$:
Spleen is the graveyard of erythrocytes.
In the light of the above statements,choose the most appropriate answer from the options given below:

Grouping of $ABO$ blood is based on the

Name the major site where $RBCs$ are formed.

Which of the following is found in the highest concentration in blood plasma?