Which of the following methods tells you which layer of rock is oldest but does not tell you exactly how old

Monitor and apply fix up strategies

Which would best keep the oxygen cycle stable? a. cutting down jungles to create farmland b. eliminating parks in large cities c. dumping toxic chemicals into the ocean d. reducing the amount of deforestation d. reducing the amount of deforestation

Which is a function performed by stem cells in the skin a. replacing lost skin cells b. making cells for the intestines c. growing new organs d. differentiating into brain cells plz apex