Given that \(n\) number of A.Ms are inserted between two sets of numbers \(a, 2 b\) and \(2 a, b\) where \(a, b \in \mathbb{R}\). Suppose further that the \(m^{\text {th }}\) means between these sets of numbers are same, then the ratio \(a: b\) equals
(A) \(n-m+1: m\)
(B) \(n-m+1: n\)
(C) \(n: n-m+1\)
(D) \(m: n-m+1\)