______ is a group of cells similar in structure and function.

Correct option is C

Tissues are groups of cells that have a similar structure and act together to perform a specific function. Different tissues make up organs.
There are four main types of tissues in the human body: epithelial tissue, connective tissue, muscle tissue, and nervous tissue. Each type of tissue has a specialized function and plays a critical role in maintaining the overall health and function of the body.