Which of these types of motors or engines are heat engines?

Question

a. an automobile engine
b. an electric motor
c. a steam turbine

Answer 1

Heat engines produce mechanical or electrical energy from heat. That excludes electric motors from consideration.

A steam turbine can in some cases be one PART of a heat engine, but a burner, geothermal source or nuclear reactor would have to be part of the complete heat engine system.