The correct answer is A. Cell Theory.
Cell Theory is the scientific theory that all living things are made up of cells, that cells are the basic units of life, and that new cells are produced from existing cells.
The theory was first proposed in 1839 by Matthias Schleiden and Theodor Schwann. They observed that all plants and animals are made up of cells, and that cells are the basic units of structure and function in living things.
In 1855, Rudolf Virchow proposed the third tenet of Cell Theory, which states that new cells are produced from existing cells.
Cell Theory is one of the most important and fundamental theories in biology. It provides a basic framework for understanding the structure and function of living things.
Atomic Theory is the scientific theory that all matter is composed of tiny particles called atoms. Atoms are the basic units of matter, and they are the building blocks of all elements.
Bohr’s Theory is a model of the atom that was proposed by Niels Bohr in 1913. Bohr’s Theory states that the electrons in an atom orbit the nucleus in fixed orbits, or shells. The electrons can only move between orbits if they absorb or emit energy.
None of the above is the correct answer.