If one positive integer is greater than another positive integer by 3, and the difference of their cubes is 189, what is their sum?  Choose the most appropriate option:
A) 6	B) 7	C) 8	D) 9	E) 10
1^3 = 1   2^3 = 8   3^3 = 27   4^3 = 64   5^3 = 125   6^3 = 216   The two numbers are 3 and 6.   The answer is 9.
<result>D</result>
If one positive integer is greater than another positive integer by 3, and the difference of their cubes is 189, what is their sum?