Answer:
Obviously C-14 Method...
Explanation:
First things to clear first that the dendrochronological analysis is used only for plants that are alive. the second thing to under stand is that this analysis of a wood fragment would only give ages according to the size and number of rings present in the bark of wood.
The C-14 is a highly effective way because it can give aging analysis even for a million years or so and scientists used it everyday to predict the age by analyzing decayed organic carbon isotope C-14 present in every life form dead or alive on Earth.