Uranium-238 is found only in igneous or volcanic rocks. They can date a very ancient fossil also but carbon cannot date and ancient fossil. Trees are not very ancient. Carbon-14 can be used to measure only fossils of recent age.
Red blood cells have no mitochondria and generate energy anaerobic. So, the answer would be B. You can easily eliminate A. and C. because they mention that blood cells have a mitochondria, but they don’t.
