Carbon 14 has a half life of 5,730 years. Scientists measure how much carbon 14 the rock has. For objects older than 50,000 years, scientists will test the age of the things surrounding it.
I believe that the answer is A, if I am not mistaken!
The answer is the nervous system.
Hope this helps!
What are you writing write full
My Answer: DNA cloning.
Hope I helped! :D