A student wanted to keep a pet rat. He kept it inside a closed cage and found that the rat died the next day. Select the reason behind the death of the rat

The correct option is "It did not get air to breathe".

To understand why this is the correct reason, let us look at the basic needs of living organisms step-by-step:
1. All living creatures, including rats, require a continuous supply of oxygen to stay alive. Oxygen is a vital gas present in the air.
2. Living things obtain oxygen through the process of respiration (breathing). In this process, they inhale fresh air to take in oxygen and exhale carbon dioxide.
3. The rat was kept inside a closed cage. A closed, airtight cage prevents fresh air from entering and circulating inside the space.
4. As the rat continues to breathe inside the closed cage, it quickly consumes the limited amount of oxygen available within that small, sealed space. Once this oxygen is depleted and replaced by carbon dioxide, the rat can no longer breathe.
5. Without air containing oxygen to breathe, the cells in the rat's body cannot produce energy, leading to organ failure and death within a very short period (such as by the next day).

While food, water, and space are also essential for long-term survival, a lack of air to breathe causes death much faster than a lack of food or space.