We're being asked to identify which Law or Theory states that “In a chemical reaction, matter is neither created nor destroyed”.
Let's define each options first:
a. Law of Conservation of Mass - states that matter can neither be created nor destroyed, all that happens is that it changes forms.
The statement, "In a chemical reaction, matter is neither created nor destroyed" is called:
A. the Law of Conservation of Mass
B. Dalton's Atomic Theory
C. the Scientific Method
D. the Law of Multiple Proportions
E. the Law of Definite Proportions