In high-altitude regions,the $R.B.C.$ count in humans will . . . . . . .

Which of the following statements is correct regarding breathing?

People who have migrated from the plains to an area adjoining Rohtang Pass about six months back:

Describe the metabolic processes of living organisms in relation to gas exchange.

Read the steps of respiration and arrange them in the correct sequence.
$I$ - Transport of gases by blood.
$II$ - Utilization of $O_2$ by cells for catabolic reactions and release of $CO_2$.
$III$ - Diffusion of gases across the alveolar membrane.
$IV$ - Diffusion of $O_2$ and $CO_2$ between blood and tissues.

Which of the following two changes occur in humans when they move to high altitudes (above $3,500 \ m$)?
$(1)$ Increase in red blood cell size
$(2)$ Increase in red blood cell production
$(3)$ Increase in breathing rate
$(4)$ Increase in thrombocyte count