Ineed with one biology question plea

Well, the most popular theory is the Big Bang Theory. This theory has made many people believe it and helped figure out the problem. Although, no one knows if it's true or not

No, they don't. There are various speculations about the origin, but none of them are accepted worldwide, or even by a majority of scientists. 
Part of the reason for this, is that none of the speculations are testable. They don't make unique predictions about things we can perceive or measure. 
If this assignment is about the "big bang" theory, then let me point out that the BB theory is not about the origin of the universe. It is an explanation of what happened AFTER the origin. It says nothing about what happened in the first tinniest fraction of a second.
Scientists will tell you that viewpiont which suits their own materialistic perceptions .. They will never suggest for example that the universe originated by collective thought. Scientists belong to a kind of cult which demands that they must convert all subjective perceptions into objective ones which everyone agrees on. In other words their task is to get everyone to agree with the form and functions of the physical universe. It is a materialist philosophy.

Ithink due to shortage of water