A. a small structure within a cell. b. a structure composed of several tissue types. c. the basic structural unit of all living organisms. d. a group of organs with a common set of functions. e. a group of cells with similar structure and function.

An organ is:

A. a small structure within a cell. b. a structure composed of several tissue types. c. the basic structural unit of all living organisms. d. a group of organs with a common set of functions. e. a group of cells with similar structure and function

b. a structure composed of several tissue types.

Explanation:

There are several levels of organization of life in living things, which progresses from simple structural level to more complex ones.  The cell is the basic unit of life capable of carrying out virtually all life’s functions. Cells are composed of several structures known as organelles. Similar cells with similar functions associate to form a tissue at the tissue level.  The next level of organization is organ level. Several tissues associate together to form an organ. An example of an organ is the liver. Several organs can as well associate together to form the organ system at the system level of organization.

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