An inventor proposes an engine that utilizes the boiling water of a hot spring and suggests it

Question:

An inventor proposes an engine that utilizes the boiling water of a hot spring and suggests it can operate with an efficiency of 22% in an area where a local stream has an average temperature of 12°C. Such a proposal is:
(A) Not possible
(B) Very likely possible
(C) Possible but improbable
(D) Possible many days of the year