Which of the following processes would be a violation of the second law of thermodynamics? (there may be more than one correct choice.)

a: all the kinetic energy of an object is transformed into heat.
b: all the heat put into the operating gas of a heat engine during one cycle is transformed into work.
c: a refrigerator removes 100 cal of heat from milk while using only 75.0 cal of electrical energy to operate.
d: a heat engine does 25.0 j of work while expelling only 10.0 j of heat to the cold reservoir.