In gas-liquid contact operation, the number of ideal stages, $${\text{N}} = \frac{{{{\text{x}}_{\text{a}}} - {{\text{x}}_{\text{b}}}}}{{{{\text{x}}_{\text{b}}} - {{\text{x}}^{ * {\text{b}}}}}}.$$   This is true when the stripping factor 'S' is

A. S > 1

B. S < 1

C. S = 1

D. S = $$\infty $$

Answer: Option A