Which type of white blood cells are concerned with the release of histamine and the natural anticoagulant heparin?

If you suspect a person has a major deficiency of antibodies,which of the following would you look for as definitive evidence?

Which of the following substances,if introduced into the bloodstream,would cause blood clotting at the site of introduction?

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	$(v)$ $20-25\%$

In human blood,the oxygen carrier is

$A$ person with an unknown blood group under the $ABO$ system has suffered significant blood loss in an accident and requires an immediate blood transfusion. His friend,who has a valid certificate of his own blood type,offers to donate blood without delay. What would be the blood group of the donor friend?