Consider the following statements:

I: If x, y, and z are in GP and tan^-1x, tan^-1y, tan^-1z are in AP, then x = y and y ≠ z.

II: If the sum of m terms of an AP is n and the sum of n terms is m, then the sum of (m + n) term is -(m + n).

III: Sum of GP 3 + 9 + 27 + 81... where there are 5 terms is 363.

Which one of the following is correct in respect of the above statements?