Answer:
A) all living things are made of cells.
Explanation:
Cell theory is presented by Matthias Schleiden in 1839. Cell theory states that "all the living organisms are madeup of one or more cells". Cell contains nucleus in the center which controls all activities of the cell. The organelles which are present in the cell are mitochondria, lysosomes, ribosome, cytoplasm, endoplasmic reticulum, golgi bodies and vacuoles. Every organelle has its own function.
