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: The leg straightens when muscle fibers get shorter.
[A]: What happens to your leg when muscle fibers shorten?


[Q]: Fact: the mass of the sun causes its gravity on Earth.
[A]: What causes gravity on the Earth?


[Q]: Fact: Some viruses are also enclosed by phospholipids fat and molecules.
[A]:
What are some viruses enclosed by?