Explanation:
In a neutral atom, the electrons are bound to the nucleus by the electromagnetic force.

Electromagnetic Force:
The electromagnetic force is one of the four fundamental forces of nature. It is responsible for the interaction between electrically charged particles. This force is characterized by its strength and range. It is much stronger than the gravitational force but has a shorter range.

Electrons and Nucleus:
In an atom, the nucleus is composed of positively charged protons and uncharged neutrons. The electrons, which are negatively charged, orbit around the nucleus. The electromagnetic force between the positively charged nucleus and the negatively charged electrons keeps the electrons bound to the nucleus.

Electrostatic Force:
The electrostatic force is a specific type of electromagnetic force that occurs between charged particles at rest. It is responsible for the attraction or repulsion between electrically charged objects. In the case of an atom, the electrostatic force between the negatively charged electrons and the positively charged nucleus contributes to the overall electromagnetic force that keeps the electrons bound.

Friction Force:
Friction force is a force that opposes the relative motion or tendency of motion between two surfaces in contact. It is not involved in the binding of electrons to the nucleus in an atom.

Centripetal Force:
Centripetal force is the force that acts towards the center of a curved path, keeping an object moving in a circular motion. While the electrons in an atom do move in orbits around the nucleus, the centripetal force is not the primary force responsible for binding the electrons to the nucleus.

Conclusion:
The correct answer is option 'B' - Electromagnetic force. The electromagnetic force between the positively charged nucleus and the negatively charged electrons is responsible for binding the electrons to the nucleus in a neutral atom.