Answer:
Limited to the tools 50,000 years old is the correct answer.
Step-by-step explanation:
Chemist Willard Libby was the first one to realize that C-14 can be used for dating the fossils. Since its discovery it became a valuable tool for the paleontologists, archaeologists and for finding dates.
There are several challenge to the method of radiocarbon dating, The samples can be easily contaminated by the other carbon containing materials , inorganic materials cannot be dated using radio carbon dating. This method is expensive and age is also a hurdle. The samples older than 40,000 years can't be dated easily as very few levels of carbon-14 is left in them.