An Ideal Carnot Engine Operating Between a Warm Reservoir of Unknown

Multiple Choice

An ideal Carnot engine operating between a warm reservoir of unknown temperature and a cold reservoir at $1.76 \mathrm {~K}$ has an efficiency of $11.0 \%$ . What is the temperature of the warm reservoir?

A) $1.98 \mathrm {~K}$
B) $157 \mathrm {~K}$
C) $0.160 \mathrm {~K}$
D) $0.180 \mathrm {~K}$