If the temperature rises from 20°C to 25°C, how many degrees has it risen?

The question asks for the change in temperature when it rises from 20°C to 25°C. To find the increase in temperature, you can simply subtract the starting temperature from the final temperature.

So, you take the final temperature (25°C) and subtract the initial temperature (20°C):

25°C - 20°C = 5°C

This calculation shows that the temperature has risen by 5 degrees. Therefore, it is clear that the correct answer is the one that states the temperature increase is 5 degrees. This understanding is crucial for solving similar problems involving temperature changes, where simple subtraction of two temperatures will give you the change in degrees.