Heat transfer please help as soon as possible

In an experiment, a hot fluid enters a heat exchanger with 45C and leaves with 32C. Doubling the flow rate of the cold fluid does not lead to any significant change in these temperatures. How do you interpret these findings? The heat transfer in the cold fluid is very high compared to the other heat transfer resistances The flow rate of the cold fluid is too low The flow rate of the cold fluid is too high The heat transfer in the cold fluid is very low compared to the other heat transfer resistances