Question
Answers

Oxygen is returned to the atmosphere mainly by:
A.Burning of fossil fuels
B.Respiration
C.Photosynthesis
D.Fungi

Answer Verified Verified
Hint:Oxygen is an important component of everyday life. We cannot survive without oxygen. It is a component of several biological molecules such as carbohydrates, proteins, nucleic acids, and fats.

Complete step by step answer:
The burning of fossil fuels results in the emission of ${ CO }_{ 2 }$ in the atmosphere.
The breakdown of glucose into our body with or without the use of oxygen to produce energy is called respiration. Respiration is the process used in the water cycle.
Photosynthesis is a procedure that changes over ${ CO }_{ 2 }$ into a natural mixture and starch (sugar) utilizing vitality from daylight. ${ O }_{ 2 }$ is additionally discharged during this procedure. Oxygen is taken by human beings and animals and they release carbon dioxide in the air. This ${ CO }_{ 2 }$ is taken up by plants for photosynthesis and thus they release ${ O }_{ 2 }$ in the atmosphere. In this way, oxygen is taken and returned back.
Fungi are multicellular eukaryotic organisms. They are saprophytes and feed on dead organic material.
Hence, we can say that oxygen is returned to the atmosphere mainly by photosynthesis.

The correct option is C.

Note:
The possibility to make a mistake is that you may choose options A and B. But in the burning of fossil fuels ${ CO }_{ 2 }$ gas is emitted in the atmosphere and in respiration water is formed. So, in these, there is no oxygen gas emitted in the atmosphere.