Which of the following is prohibited by the 2nd law of thermodynamics?
(a) a device that converts heat into work with 100% efficiency
(b) a device that converts work into heat with 100% efficiency.
(c) a device that uses work to supply x heat at high temperature while taking in y heat at lower temperature. where x> y.
(d) a device that converts work into heat with > 100% efficiency

(A) A device that converts heat into work with 100% efficiency

It clearly violates the second law of thermodynamics because it warns that while all work can be turned into heat, not all heat can be turned into work. Therefore, despite the innumerable efforts, the efficiencies of the bodies have only been able to reach 60% at present.

tube or goog with be a great resource to with that question