Oxygen and hydrogen are both elements that are found as gases at room temperature. When oxygen combines with hydrogen, they produce the compound water according to the chemical equation below. O2 + 2 H2 2 H2O

Water is a liquid at room temperature. This example shows that in a chemical equation, the substance that is produced

A.
has properties that are different from the original substances.
B.
can only contain a single type of element.
C.
contains fewer types of elements than the original substances.
D.
always has the same properties as the original substances.