Let f(x) = (x - 1)/(x + 1), x ∈ R{0, - 1, 1). If fⁿ+1(x) = f(fn(x)) for all n ∈ N, then f⁶ (6)+ f⁷(7) is equal to:
(A) 7/6
(B) -3/2
(C) 7/12
(D) -11/12