Identify the line segment on the diagram where specific heat of liquid water is used to calculate energy flow. So remember here this is a cooling curve above 100�C. We exist in the gaseous phase. Remember, we're looking for liquid water. Once we reach 100�C, that's where we undergo our first phase change. Here we're going from a transition of a gas to a liquid.

Now we want only the liquid form of water and that starts to occur at Point C. Going down from C to D is where we finally have only liquid water. D to E would be us going from a liquid to a solid, another phase change, and then from E to F would be our solid form.

Now if we look here on line segment CD, since we're undergoing a temperature change, because we're going from 100 to 0, we'd use Q=MCΔT here, where here our specific heat capacity C would be the specific heat capacity of liquid water. If we're dealing with the gas, we'd still use Q=MCΔT, which would be the specific heat of gaseous water. And then here it would be the specific heat of ice.

Now again going back to the question, we're looking for liquid water. So that would mean the answer is option C. Line segment CD would have the specific heat of liquid water.