Highest content of iron is found in

To prevent blood clotting, donor blood is treated with $..........$.

Match the different types of leucocytes (Column-$I$) with their percentage of occurrence (Column-$II$) in a healthy adult and choose the correct answer.

Column-$I$	Column-$II$
$A$. Neutrophils	$(i)$ $6-8\%$
$B$. Lymphocytes	$(ii)$ $60-65\%$
$C$. Monocytes	$(iii)$ $0.5-1\%$
$D$. Basophils	$(iv)$ $2-3\%$
$E$. Eosinophils	$(v)$ $20-25\%$

Which enzyme is responsible for the conversion of inactive fibrinogens to fibrins?

Which of the following statements are correct regarding thrombocytes?
$I$ - Also known as blood platelets.
$II$ - They are cell fragments.
$III$ - Produced from megakaryocytes.
$IV$ - Their count in a normal individual ranges from $3,50,000$ to $6,00,000$ per $mm^3$.
$V$ - Involved in the process of blood coagulation.

Which of the following prevents the conversion of prothrombin to thrombin in an undamaged blood vessel?