Answer:
Carbon-13
Explanation:
Carbon have three isotopes. Isotopes are the atoms of the same element which has a different number of neutrons. Carbon has 3 isotopes.
Carbon-12 : 6 electrons I 6 protons I 6 neutrons
Carbon-13 : 6 electrons I 6 protons I 7 neutrons
Carbon-14 : 6 electrons I 6 protons I 8 neutrons