Kelly ran electricity though a sample of water using electrolysis. The water changed into two gases, X and Y. It was not possible to break down the gases X and Y into simpler particles.
 Which statement is best supported by this evidence?
 A. 
 Water is an element.
 B. 
 The gas Y is water vapor.
 C. 
 The gases X and Y are compounds.
 D. 
 The gases X and Y are elemen