An atom with an atomic number of 12 and a mass number of 25 can best be described by which of these?
A) An atom that contains 12 protons and 13 neutrons.
B) An atom that contains 13 protons and 12 neutrons.
C) An atom that contains 12 protons and 25 neutrons.
D) An atom that contains 25 protons and 12 neutrons.