A rock contains 0.37 mg of Pb-206 and 0.95 mg of U-238. The half-life of the decay series U-238 to Pb-206 is 4.5 × 10⁹ years. Assuming no Pb-206 was present in the rock initially, how old is the rock?
A) 1.7 × 10⁹ years
B) 5.2 × 10⁹ years
C) 2.7 × 10⁶ years
D) 2.4 × 10⁹ years
