Identify the mismatched pair.
1) WBC `to` Oxygen transportation
2) RBC `to` Microscopic policeman
3) Platelets `to` Blood coagulation.

Explanation

(1)The relative amount of gases and their combining capacity with haemoglobin and other substances in blood determine their transport via blood in the body.
(2)When oxygen present in the air is within normal limits (around 21%) then almost all of it is carried in the blood by binding to haemoglobin , a protein present in the red blood cells.
(3)As oxygen is diffused in the blood , it rapidly combines with the haemoglobin to form oxyhaemoglobin.
(4)Not only haemoglobin can combine with oxygen , but the reverse can also happen to yield a molecule of haemoglobin and oxygen.
(5)Carbon dioxide is usually transported as bicarbonate , while some amount of it combines with haemoglobin and rest is dissolved in blood plasma .
`Hb+O_2 to Hb(O_2)` (in lungs)
`HbO_2 to Hb + O_2` (in tissues )