Respuesta :
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.
Answer:
The correct answer would be an option a.
Cell theory was mainly formulated Matthias Schleiden and Theodor Schwann in 1839.
They postulated that:
All cells arise from pre-existing cells.
Each living organism consists of one or more types of cells.
The cell is a basic functional and structural unit of all living organisms.
Thus, option a. would be the correct answer.
