Answer:
B) Neutrons
Explanation:
The nucleus of an atom is made by two types of particles: protons and neutrons.
Protons are positively charged particles, therefore they exert an electrostatic force on each other. In particular, since two protons have same-sign charge, the electrostatic force between them is repulsive. This means that all the protons within a nucleus repel each other: without the presence of another force, a nucleus would disgregate.
However, there is another type of particle in the nucleus: the neutron. Neutrons are electrically neutral, so they do not exert any electrostatic force on protons or on each other. But both types of particles (protons and neutrons) exert on each other another force, which is called strong nuclear force. This force is attractive, so that protons and neutrons attract each other inside the nucleus, and the nucleus does not disgregate.
