Question

what is a tissue?
a group of disconnected cells having the same function.
a collection of single cells floating in the blood always.
a variety of connected cells performing various functions.
a set of connected cells having the same function.

Explanation:

In biology, a tissue is defined as a group of connected cells that have the same function. Disconnected cells or cells with various functions do not meet the definition of a tissue, and tissues are not just single - cell collections in the blood.

Answer:

A set of connected cells having the same function.