What do all atoms of all elements have in common?

We need to understand what an atom is in order to respond to this question. A nucleus, which is an extremely dense core, makes up an atom. The three primary subatomic particles that make up the nucleus are subatomic particles. Protons, neutrons, and electrons make up the subatomic particles.

An atom is found to be the smallest yet most complex unit of the matter surrounding us. 

All the atoms consist of three subatomic particles but they differ in number. These sub-particles of an atom are electrons, neutrons, and protons.

The tiniest yet most intricate unit of the substance that surrounds us is an atom. Together, these atoms create an element. Each element has distinct chemical and physical characteristics that may be used to identify it. However, by examining the structure of an atom, it is possible to determine what features they share. The electron is the outermost subatomic particle. These electrons have a negative charge and move in an atomic orbit around the nucleus. These outside electrons are also known as an element's valence electrons.

The proton and neutron are located on the inner side of an element's nucleus, where they make up the majority of the atom. While neutrons have a neutral charge, protons are stable, positively charged subatomic particles. In comparison to protons and neutrons, which have approximately the same mass of grammes, electrons have a substantially lower mass of grammes. The mass of an electron is not taken into account when determining the overall mass of an atom due to its low mass.

Hence option (A) is correct.