In a living organism, what is an organ? ОА.
a structure that provides a specific service within a cell
Св.
a group of similar cells that perfom a common function
C.
functional unit, or building block, of all organisms smallest unit that can carry on the activities of life
a structure composed of a number of tissues that work together to perform a specific task
0.

a structure composed of a number of tissues that work together to perform a specific task

Explanation:

unicellular organisms, like bacteria, are able to perform all life functions within one single cell. multicellular organisms need many different types of cells to carry out the same life processes. each of these special types of cells has a different structure that it perform a specific function.