. Why do mountaineers carry oxygen cylinders with them
(a) The air at high mountains becomes less.
(b) Amount of carbon dioxide is more on high mountains
(c) The cylinders help them balance their weight.
(d) None of these.
(a) The air on higher mountains becomes less as the layer of atmosphere is thin there. As a result amount of oxygen also decreases and the mountaineers have to carry oxygen cylinders with them.