Question

Mountaineers and divers carry oxygen cyclinders along with them

Answer 1

Mountaineers :

The person who used to climb mountains.

Divers :

The person who used to do underwater.

So,

Both mountaineers and divers goes upwards and downwards respectively.

And as we know that,

the oxygen level decreases when we go upwards or downwards.

So,

Mountaineers carry oxygen cylinders with them because the presence of oxygen decreases when we go up.

And divers also carry oxygen cylinders with the them as going deep in sea decreases the oxygen.