How many molecules of $O_2$ can one molecule of hemoglobin carry?

$CO_{2}$ diffuses into ...$A$... and forms $HCO_{3}^{-}$ and $H^{+}$. At the ...$B$... site where $pCO_{2}$ is low, the reaction proceeds in the opposite direction.
Thus, $CO_{2}$ is trapped as ...$C$... at the tissue level and transported to alveoli is released out as ...$D$...
Select the right choice for $A, B, C$ and $D$ to complete the given $NCERT$ statement.

Choose the incorrect sentence from the following.

What is the effect of $CO_2$ concentration on the dissociation of oxyhemoglobin called?

The graph plotted between the percentage saturation of hemoglobin with oxygen and the partial pressure of oxygen $(pO_2)$ is known as:

Body tissues obtain $O_2$ from hemoglobin. The dissociation of oxyhemoglobin in the tissues is primarily caused by which of the following conditions?