What is composed of a variety of cell types that work together to perform similar functions?

The correct answer is that a tissue is composed of a variety of cell types working together to perform similar functions. Tissues are groups of cells that share a common structure and function, enabling them to collaborate in carrying out specific activities essential for the organism's overall health and functionality. For example, muscle tissue consists of muscle fibers (cells) that work together to facilitate movement, while connective tissue includes various cells that support and bind other tissues and organs.

An organ is a larger structure that is made up of multiple types of tissues working together to perform specific functions. An organ system comprises several organs that collaborate to achieve broader physiological processes. A chromosome, on the other hand, is a structure within cells that contains genetic material and is not related to the collaborative function of cell types within tissues. Thus, tissue is the correct term for the scenario described in the question.