The graph shows the average annual water temperature in holbrook pond. which part of the graph shows the steepest increase in the pond’s temperature?

The top portion of the crest

Explanation:

In the given graph, the temperature of the pond has increased by the highest degrees while moving from second colored box to third colored box, thus it shows the steepest increase in the pond’s temperature

If we look at the temperature increase at each red box , we will get the following

Temperature at red box 1 – 5 degree celcius

Temperature at red box 2 – 12.5 degree celcius, thus the temperature rose by 7.5 degrees while moving from box 1 to box 2

Temperature at red box 3- 22.5 degree celcius, thus the temperature rose by 10 degrees while moving from box 2 to box 3

After this the temperature starts falling.