In the given figure, B and C are the centres of the two circles. ADE is the common tangent to the two circles. If the ratio of the radius of both the circles is 3 : 5 and AC = 40, then what is the value of DE?

A. $$3\sqrt {15} $$

B. $$5\sqrt {15} $$

C. $$6\sqrt {15} $$

D. $$4\sqrt {15} $$

Answer: Option D