Which of the following plants possesses sunken stomata?

The respiration rate is lowest while

Select the correct option:
$(1)$ The respiratory rhythm center for breathing regulation is located in the medulla oblongata of the brain.
$(2)$ Each hemoglobin molecule can carry a maximum of $4$ molecules of $O_2$. (Note: The original question mentioned $CO_2$,which is incorrect; hemoglobin primarily transports $O_2$.)

Select the incorrect sentence for respiration.

What is the last step involved in respiration?

Match the partial pressure of carbon dioxide in different parts involved in diffusion in comparison to the atmosphere.

Column-$I$	Column-$II$ ($mm\, Hg$ pressure)
$P$. Atmospheric air	$I$. $40$
$Q$. Tissues	$II$. $45$
$R$. Oxygenated blood	$III$. $0.3$