The correct answer is C. There is a large amount of rain or snow in the air.
Step-by-step explanation
According to the fragment of the question that states that "To use a radar, a weather tower sends out radio waves and then detects the waves that are reflected back to the tower" it is possible to infer that the radar waves that are reflected towards the tower They are the product of the collision of these waves with an object that is in the air such as rain. Therefore, in the case in which a large number of radio waves are reflected towards the tower in a particular area, it can be said that this is due to a large number of objects in the air in this area such as rain or snow. So the correct answer is C. There is a large amount of rain or snow in the air.