Answer: Igneous Rock
Explanation: Radiometric dating is used to date rocks by measuring the decay of their composite materials. Stable isotopes remain the same over time while the nucleus of an unstable or radioactive isotope will decay to form other isotopes .
Dating rocks using Isotopic methods uses the decay time of the isotope in the rock to assess its age. The accuracy of this method is assured by the fact that when these isotopes decay, they are retained in the rock. Isotopic dating is not very accurate in sedimentary rocks because they contain particles from older rocks.