Decay of radioisotopes follows first order kinetics. Radioisotope $$\text{U}^{238}$$ undergoes decay to a stable isotope, $$\text{Th}^{234}$$. The ratio of the number of atoms of $$\text{U}^{238}$$ to that of $$\text{Th}^{234}$$ after three half lives is

A

$$\frac{1}{3}$$

B

$$\frac{3}{4}$$

C

$$\frac{1}{4}$$

D

$$\frac{1}{7}$$