Final answer:
d. Geologists can study the age of the Earth using fossils, layers of rocks, and radioactive elements in rocks.
Step-by-step explanation:
d. Geologists can study the age of the Earth using fossils, layers of rocks, and radioactive elements in rocks. Fossils can help determine the relative age of rock layers and provide evidence for when organisms lived on Earth. Layers of rocks can be used to establish the order in which rocks and fossils appeared, allowing scientists to trace the history of Earth and life on Earth.
Radioactive elements in rocks, such as isotopes, can be measured to calculate the age of the rocks. By determining the ratio between parent and daughter isotopes and knowing the rate of decay, geologists can determine the age of the rocks.