The atomic number of carbon is six, which means that a carbon atom has six protons. carbon has three naturally occurring isotopes: carbon-12, carbon-13, and carbon-14. what is true about carbon and its isotopes?

The true about carbon and its isotopes is that the isotopes define the average atomic mass of the element in the periodic table taking into account the natural occurrence, it means how abundant the isotope is in nature.

Another fact of the carbon is that the most abundant isotope is carbon-12 with around 98.93 % and for this reason the average atomic mass is 12.0107.

the other two isotopes are carbon-13 with an abundance of 1.07% and the carbon-14 it is an instable isotope it means the carbon-14 decays in other elements such a nitrogen-14 by losing beta particles in its atoms (beta decay)  and hence emit energy.

This is the reason why carbon-14 is known as a radioactive isotope.

B and D

Explanation:

B - All carbon atoms have six protons and six electrons.

D -  Atoms of some naturally occurring carbon isotopes may have six neutrons.

That's just how it is