According to atomic theory, all matter is made up of particles called atoms Why is this considered to be a theory and not a law?

A. Atomic theory may change when new evidence is found that does not support the theory. A law has been proved with scientific evidence.
B. Atomic theory is a description based on observations. A law is based on mathematical calculations.
C. Atomic theory is an explanation of the nature of atoms. A law describes natural events but does not attempt to explain them.
D. Atomic theory is supported by research. A law is merely an educated guess​