Why are cells so smallest are cells so small

They need a large surface area relative to the volume they contain to function right

Cells in our body is too small because due to their tiny nature they in large amount of nutrient and exist the waste quickly.

Explanation:

If the cell in our body grows for the limit, the materials are fast to accommodate in the cells. Cell are too small so they can maximize their surface area to volume, the smaller allows the molecules and ions in to our body for high level.

The small nature of the cell is easy to accommodate the materials in our body and gives high nutrients.