What Is the Efficiency of an Ideal Carnot Engine Operating $1.0$

Multiple Choice

What is the efficiency of an ideal Carnot engine operating between a reservoir in which ice and water coexist, and a reservoir in which water and steam coexist? The pressure is constant at $1.0$ atm for both reservoirs.

A) $100 \%$
B) $1.0 \%$
C) $0.27 \%$
D) $15 \%$
E) $27 \%$