A geologist is trying to date a sequence of sedimentary rocks with abundant fossils. The sedimentary rocks are mostly sandstone. Within the rock sequence there is a distinctive clay layer that under closer inspection is fine-grained volcanic ash. Which of the following is the best way to obtain an absolute date for the sequence of rocks? a. Carbon date the fossils b. Potassium-Argon date the sands c. Uranium-lead date the zircons in the ash d. Identify the index fossils