Answer:- A tissue is a group of similar cells that together to perform a certain function.
Explanations:- A molecule is made up of atoms and not cells.
An organ is a group of tissues that together perform a specific function in the body of an organism.
An organ system has a group of organs that together perform a specific function in the body or an organism.
A tissue is a group of similar cells that together to perform a certain function.
So, the right answer is Tissue.
