$I.$ $pO_2$ is the major factor which affects the binding of $CO_2$ with haemoglobin.
$II.$ $pCO_2$ is low and $pO_2$ is high in tissues.
$III.$ $RBC$ contains a very high concentration of carbonic anhydrase.
$IV.$ Every $100 \; mL$ of deoxygenated blood delivers approximately $4 \; mL$ of $CO_2$ to alveoli.
Select the combination of right statements.

• A
  $I, III$ and $IV$
• B
  $I, II$ and $IV$
• C
  $I, II$ and $III$
• D
  $II, III$ and $IV$