What is the answer to this question?

Lower right corner

Explanation:

The information that the temperature rises 3 degrees per hour will tell us the slope here. The slope is rise/run = 3/1 = 3. Each time we move up 3 on the y axis, we move 1 spot to the right.

As you can see in the bottom right hand corner graph, we start off at a temperature of 20 degrees. This is the point (x,y) = (0,20)

Then one hour later (x = 1), the temperature y bumps up to y = 23. Another hour passes by (x = 2) and y becomes y = 26. And so on.