How does a law differ from a theory?
a law is a theory that has been proven to be true and universal.
a theory is a group of hypotheses that prove a law is true.
a law is a statement of fact, but a theory is an explanation.
a theory is a proposed law that has not yet been peer reviewed.

Option C, A law is a statement of fact, but a theory is an explanation.

Explanation:

A law is basically a fact established through research and it remains constant under all circumstances while theory is an explanation to this phenomenon behind this law. Theories are flexible and can improvise with further research and finding while a law remains constant.  

For example – Expansion of universe is a law while the explanation to this phenomenon such as big bang is a theory.  

cell regulation is conducted by special proteins.