Answer:
D. It's nucleus is heavier due to two more nuetrons
Explanation:
Carbon-14 is an isotope of carbon. The '14' in carbon-14 is it's mass. The mass is the sum of the protons + neutrons (electrons excluded because they have virtually no mass - equal to 1/1836) so the nucleus must be heavier than that of carbon-12. All isotopes of carbon have the same number of protons, if it had fewer or more protons it would be a different element and not carbon.
