Answer:
C-14 from fossil had reached itshalf life
Step-by-step explanation:
For radiactive isotopes (such as Carbon-14), per definition; the semi life or semi disintegration period; is defined as the time for which a certain mass isotope mass disintegrates to half of the atoms that make it up
For Carbon-14, this semi life period is 5730 years , and for the above example, as it is mentioned that we originally had 254 grams of C-14 but we currently have 127 grams (this is, exaclt half of the original mass of 254 grams), this leads us that 5730 years have passed since the original mass and the final mass (that is, one semi life period of C-14)