Final answer:
A)The numbers on the periodic table represent an element's atomic number (the number of protons, and by extension, electrons in a neutral atom) and its mass number.
Step-by-step explanation:
The numbers listed for an element on the periodic table represent its atomic number and mass number. The lesser number is the atomic number, which is the number of protons in the nucleus and defines the identity of the element.
It also indicates the number of electrons in a neutrally charged atom. The greater number is the mass number, which is the total number of protons and neutrons in the atom's nucleus.
To find the number of neutrons, you subtract the atomic number from the mass number. Therefore, the correct answer to the question is 'A. The lesser number is the number of protons, and the greater number is the mass.'