All of the statements below were part of the original cell theory proposed by schleiden and schwann with the exception of
select one:
a. viruses are not living since they are smaller than a cell.
b. the cell is the most basic unit of life.
c. all living things are composed of one or more cells.
d. all cells come from other cells

The correct answer is option a. viruses are not living since they are smaller than a cell.

The cell theory does not propose the explanation for the viruses. As the viruses were discovered by Dmitry Ivanovsky in 1892, after the cell theory was proposed.

After advancement in microscopy, in year 1838 Schleiden and Schwann proposed cell theory.

The cell theory proposed by Schleiden and Schwann suggested that all the living organism are made up of cell. These cells are the smallest unit, which can perform all the function, which is required for a life, they can also divide,  hence, it is the functional unit in all forms of life. They also said that a living organism at least have a cell or more than one cell.