Many tribes live in the high altitude of Himalayas in them

Assertion $(A):$ A person goes to high altitude and experiences 'altitude sickness' with symptoms like breathing difficulty and heart palpitations.

Reason $(R):$ Due to low atmospheric pressure at high altitude, the body does not get sufficient oxygen.

In the light of the above statements, choose the correct answer from the options given below.

Which is not a part of atmosphere

If a marine fish is placed in a fresh water aquarium, will the fish be able to survive? Why or why not?

Why do high altitude areas have brighter sunlight and lower temperatures as compared to the plains ?