An Ideal Diatomic Gas Undergoes a Two-Step Process

An ideal diatomic gas undergoes a two-step process. The process begins at a pressure p_i and volume V_i. At the end of the two-step process p_f = 1.5p_i and V_f = 3.0V_i. The first step is an isothermal expansion to a volume V', followed by an adiabatic compression to the final volume. The intermediate volume V', in terms of the initial volume is

A) 1130V_i.
B) 13V_i.
C) 3.0V_i.
D) 130V_i.