why do mountaineers carry oxygen gas cylinders with them ?

The mountaineers carry oxygen gas cylinders with them while climbing high mountains . Give reasons.

Mountaineers carry oxygen cylinders with them because

The mountaineers carry oxygen with them because:

It is observed that mountaineers carry oxygen at high altitudes. Give reason

A list of words is given in a box. Use appropriate words to fill up the blanks in the following statements Air, oxygen, wind, water vapour, mixture, combination, direction, road, bottles, cylinders. (a) The ______ makes the windmill rotate (b) Air is a ______ of some gases. (c ) A weather cock shows the ______ in which the air is moving at that place. (d)Mountaineers carry oxygen ______ with them, while climbing high mountains.

Pulmonary veins carry oxygenated blood.

Why do body cells require oxygen?