Question: The chemical formula for water is H_{2}O. What does the formula show about each element in the compound?

What is the correct answer to the question from the following choices?
pick from the following.
[+] the number of valence electrons;
[+] the charge of the compound;
[+] the mass of protons in each atom;
[+] the number of atoms of each element;
the number of atoms of each element