Approximately $97\%$ of $O_2$ is transported by $RBCs$. The remaining $3\%$ is transported by:

Select the correct option:
$(1)$ Approximately $97\%$ of $O_2$ is transported by plasma / RBCs.
$(2)$ The primary site of gas exchange is alveoli / bronchioles.

$A$: $100 \; ml$ of venous blood contains $14.4 \; ml$ of $O_2$,meaning it is still $75\%$ saturated with oxygen under normal conditions.
$R$: About $4.6 \; ml$ of $O_2$,i.e.,$25\%$,diffuses from arterial blood into the tissues during resting conditions.

How much oxygen is delivered to the body tissues by blood during one circulation (in $\%$)?

$CO$ is more toxic than $CO_2$ because:

Choose the wrong statement.