Assertion: The proton is positively charged and the electron is negatively charged.
Reason: Charge of proton is defined as positive charge and charge of electron is defined as negative charge.
A) Both assertion and reason are correct and reason is the correct explanation for assertion.
B) Both assertion and reason are correct but reason is not the correct explanation for assertion.
C) Assertion is correct but reason is incorrect.
D) Both assertion and reason are incorrect.

Hint: Protons and electrons are constituents of an atom. There is another nuclear particle inside the nucleus of the atom, the neutron. The neutron is the neutral particle along with positively charged protons and negatively charged electrons revolving around them that is the nucleus.

Complete step by step answer:
Every object in our universe when divided into smaller particles, the smallest particle which possesses all ordinary characteristics of the element, is called an atom.
Each atom consists of a nucleus and an electron cloud surrounding the nucleus. The nucleus of an atom consists of a neutron, neutral in charge and a proton, positive in charge. The electrons however are less in mass than that of the nucleus, and carry a negative charge.
The electrostatic force of attraction between the protons and electrons keeps the electrons orbiting around the nucleus providing the necessary centripetal force.
An object possesses negative charge, if the total number of electrons is larger than the number of protons. Similarly a body exhibiting positive charge means the number of electrons is less than the number of protons.
After the discovery of protons, neutrons and electrons, it was found that a single electron carries the same amount of negative charge that a single proton carries, but this charge on the proton was positive in nature.
Charge of an electron is numerically equal to \[1.6 \times {10^{ - 19}}C\] which is represented by the alphabet $e$ .
Mathematically, charge on an electron is $ - 1e$ .
Similarly as the proton carries equal and opposite amount of charge, charge of a proton would be $ + 1e$
From the above information, we can conclude that,

Both assertion and reason are correct and the reason is the correct explanation of the assertion.

Note: From the very discovery of electrons and protons, we have assigned/defined the charge on a proton as positive and charge on an electron as negative. The electron being $\dfrac{1}{{1837}}th$ part of the mass of a proton, possesses the same amount of charge. The force of attraction between the electrons and protons provide the centripetal force.