The atomic number of an isotope is 17. If it has a mass number of 35, how many neutrons does it have? O A. The isotope has 18 neutrons because isotopes contain the same number of protons. The number of neutrons is the difference in the number of protons and the mass number. B. The isotope has an atomic number of 17 and the neutrons cannot be determined without the number of protons. O C. The isotope has 18 neutrons because isotopes contain the same number of protons. The number of neutrons is the difference in the number of electrons and the mass number. D. The isotope has 52 neutrons because isotopes contain the same number of protons. The number of neutrons is the sum of the protons and the mass number.​