Which of the following work as phagocytes?

What is the primary product of hemoglobin degradation?

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:

Universal donors and universal recipients are

Leucocytes $(WBCs)$ are considered as true cells because

In which state is iron present in hemoglobin?