According to Kelvin-Planck's statement of second law of thermodynamics,

• it is impossible to construct an engine working on a cyclic process, whose sole purpose is to convert heat energy into work
• it is possible to construct an engine working on a cyclic process, whose sole purpose is to convert heat energy into work
• it is impossible to construct a device which operates in a cyclic process and produces no effect other than the transfer of heat from a cold body to a hot body
• none of the above