If the half-life of carbon-14 is about 5730 years, then a fossil that has one-sixteenth the normal proportion of carbon-14 to carbon-12 should be about how many years old?

The half-life of Carbon-14 is about 5700 years. You have found a fossil that you believe to be about 34,200 years old because it has _____ the normal (modern) expected ratio of Carbon-14C

What is it about Carbon-12, Carbon-13, and Carbon-14that makes them all carbon?
A)They all have the same number of protons plus neutrons that ischaracteristic of carbon.
B)They all have the number of protons that is characteristic ofcarbon.
C)They all have the number of neutrons that is characteristic ofcarbon.
D)They are all radioactive.
E)They are all elements.