Which of the following statements is true about the atoms of any
element?
a. they have the same number of protons as the atoms of all
other elements.
b. they have protons that are identical to the protons of all
other elements.
c. they have the same size as the atoms of all other
elements.
d. they have the same number of protons as neutrons.

b. They have protons that are identical to the protons of all

Explanation:

An element is made up of the same atoms. Atoms are the building blocks of the matter and made up of sub-atomic particles, e.g. proton, neutron, and electrons. Protons are found in the nucleus of the atom having a positive charge. All protons are identical because all give a positive charge in all elements. They are different in numbers in each element that depend upon the atomic number.  So A option is incorrect but all elements cannot have the same number of protons. Likewise, the size of the atom is also based on the number of protons and neutrons in an atom which varies according to the atomic number. Lastly, the number of protons doesn't need to be the same as protons (check the concept of isotopes for more details).

Therefore, only B option is correct.