Which pair below describes isotopes of the same element?
A. an atom 6 protons and 8 neutrons - an atom with 8 protons and 6 neutrons
B. an atom with 6 protons and 6 neutrons - an atom with 6 protons and 7 neutrons
C. an atom with 8 protons and 8 neutrons - an atom with 7 protons and 8 neutrons
D. an atom with 7 protons and 6 neutrons - an atom with 6 protons and 6 neutrons