If \(x\) and \(y\) are positive integers, which of the following is NOT a possible value for \(\dfrac{3\cdot 2^x\cdot 18^x}{6^{x+y}}?\)

A. \(\dfrac1{12}\)

B. \(\dfrac12\)

C. \(\dfrac23\)

D. \(3\)

E. \(18\)

Answer: C

Source: Manhattan GMAT