The correct answer is D) the suction line will be abnormally cold and liquid may flood back to the compressor. When the superheat setting of a thermostatic expansion valve is set too low, it allows more liquid refrigerant to enter the evaporator than is needed. This results in the suction line becoming abnormally cold, as the excessive liquid refrigerant is not fully vaporized before it reaches the compressor. This can lead to liquid flooding back to the compressor, which can potentially damage the compressor. The other options are incorrect because: A) the box temperature would not be pulled way down, as the excessive liquid refrigerant would not be fully vaporized; B) the receiver level would not be abnormally high, as the excessive liquid refrigerant is entering the compressor instead of being held in the receiver; and C) the suction line would not be abnormally warm, as the issue is too much liquid refrigerant, not too little.