Age of fossils in the past was generally determined by radio-carbon method and other methods involving radioactive elements found in the rocks. More precise methods, which were used recently and led to the revision of the evolutionary periods for different groups of organisms, include

Options

A. Study of the conditions of fossilization
B. Electron spin resonance (ESR) & fossil DNA
C. Study of carbohydrates/ proteins in rocks
D. Study of carbohydrates/proteins in fossils

Answer

2