While Taking a Hike in the Forest, You Find Some

Multiple Choice

While taking a hike in the forest, you find some fossils in layers of sedimentary rocks whose age, you later find out, is said to cover a span of 100-400 million years. You decide to send the fossils out for analysis to a company that dates rocks by radioactive decay, and, some weeks later, receive a report informing you that a volcanic ash bed associated with one of the fossils has a 1:1 ratio of ²³⁵U: ²⁰⁷Pb. Do these data support or refute the assumed age of the rocks in which the fossil was found? (Note: The half-life of ²³⁵U is about 704 million years.)

A) Yes, because the rock layers are less than 704 million years old.
B) Yes, because the ratio of ²³⁵U to ²⁰⁷Pb represents one half-life and that would be approximately 350 million years old.
C) No, because the ratio of ²³⁵U to ²⁰⁷Pb represents one half-life and that would be about 700 million years old.
D) No, because the rock layers are less than 704 million years old.