Which One of the Statements Below Is False

Which one of the statements below is false?

A) In chemical reactions, atoms are rearranged.
B) In a given compound, the atoms are always present in the same fixed numerical ratio.
C) Matter is made up of tiny particles called atoms.
D) In a sealed reaction flask, the total mass after the reaction is over, is the same as before the reaction started.
E) When hydrogen and oxygen react to form water, the mass of oxygen atoms is equal to the mass of hydrogen atoms.