The shared property between proton and electron is electrically charged which belong to the Region B marked.
Electrons and protons posses the property known as electric charge which affects the interaction with particles of electrically charged. Electrons posses negative charge and protons have positive charge. Since the charges are opposite they act like opposite poles of magnet. The opposite charges repel each each other.
The electrons and protons are hold together by the attraction between them. An atom is electrically neutral which insist that the negative charge of the electron which is exactly equal to the protons positive charge.
