Final answer:
The pressure remains constant when Freon flows through an expansion valve. The expansion valve is designed to regulate the flow of the refrigerant, allowing it to expand and decrease in pressure before entering the evaporator.
Step-by-step explanation:
The correct answer is C. The pressure remains constant.
When Freon flows through an expansion valve, the pressure of the system stays the same.
The expansion valve is designed to regulate the flow of the refrigerant, allowing it to expand and decrease in pressure before entering the evaporator.