Concept:The nucleus of an atom consists of protons and neutrons, which are collectively called nucleons.
Electrons and beta particles are not part of the nuclear structure.
Explanation:Every atomic nucleus contains protons alongside neutrons, even in light elements.
The neutron is electrically neutral, while the proton carries a positive charge.
These particles are held together inside the nucleus by the strong nuclear force.
Electrons are found in energy shells around the nucleus, never inside it.
A
β-particle is an electron or positron emitted during radioactive decay, not a permanent nuclear constituent.
Since a light nucleus already possesses a neutron, the only other particle from the list that must also exist inside it is the proton.
Answer:D. proton