Final answer:
The mass of the electron is very small compared to the proton, about 1/1836 of the proton or neutron's mass. The nucleus, containing protons and neutrons, is dense and makes up most of an atom's mass, with electrons contributing minimally. So the correct option is c.
Step-by-step explanation:
The mass of the electron compared to the proton and neutron is significantly smaller. While protons and neutrons have approximately the same mass, which is about 1836 times that of an electron, the electron has a very small mass in comparison. The correct answer to the question 'The mass of the electron is:' would be option (c) very small compared to the proton. This can also be understood when considering the nucleus of an atom, which houses protons and neutrons: the nucleus is very dense and contains almost all the mass of the atom, while electrons contribute virtually no mass.
Furthermore, protons and electrons have electrical charges of equal magnitude but opposite signs, with protons carrying a positive charge and electrons carrying a negative charge. It is also noteworthy that neutrons are electrically neutral and slightly heavier than protons but share a similar mass.