Mario believes he has found the reason that some things glow in the dark while others do not. What is the most important thing he will need to do before his theory will be accepted by other scientists?
A. Create a petition and ask everyone who believes in his theory to sign it.

B. Develop an on-line survey so people can vote on the accuracy of his theory.

C. Write a book promoting his theory.

D. Develop tests and experiments that can be repeated to prove his theory.