Answer:
B.) A woolly mammoth fossil
Step-by-step explanation:
Carbon-14 dating is normally used to find the age of a once-living object.
C and D are not accurate because they both refer to types of igneous rocks -- only sedimentary rocks can be used for Carbon Dating.
A isn't accurate because dinosaurs lived a very, very long time ago, therefore, the isotopes wouldn't be detectable during modern times.
Though woolly mammoths lived a long time ago, it is a short time compared to the long time gap between dinosaurs and modern era. Radioactive isotopes may still be present in a woolly mammoth fossil sample.