What does the atomic number of an element represent?

In physics and chemistry, the atomic number of a chemical element is the total number of protons that each atom of that element has. It is usually represented with the letter Z.

The atoms of different elements have different numbers of electrons and protons. An atom in its natural state is neutral and has an equal number of electrons and protons. A sodium atom (Na) has an atomic number of 11; It has 11 electrons and 11 protons. A magnesium atom (Mg), has an atomic number of 12, has 12 electrons, 12 protons and a uranium atom (U), which has an atomic number of 92, has 92 electrons and 92 protons.

the answer is b.) hydrogen bonds between bases.