Turn the given fact into a question by a simple rearrangement of words. This typically involves replacing some part of the given fact with a WH word. For example, replacing the subject of the provided fact with the word "what" can form a valid question. Don't be creative! You just need to rearrange the words to turn the fact into a question - easy! Don't just randomly remove a word from the given fact to form a question. Remember that your question must evaluate scientific understanding. Pick a word or a phrase in the given fact to be the correct answer, then make the rest of the question. You can also form a question without any WH words. For example, "A radio converts electricity into?"

[Q]: Fact: deepening rivers cause the loss of topsoil.
[A]: Deepening rivers cause?


[Q]: Fact: the population divided by the area is the average number of individuals per unit of area or volume.
[A]: What is the average number of individuals per unit of area or volume?


[Q]: Fact: Cancer Mitosis is out of control.
[A]:
Mitosis is out of control due to what?