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?"

Example Input: Fact: Plasma cells are activated B cells that secrete gammaglobulins.
Example Output: What is secreted by plasma cells (activated B cells) ?

Example Input: Fact: Heating a filament is helpful for seeing in the dark.
Example Output: What is helpful for seeing in the dark?

Example Input: Fact: a mirror is used for reflecting images.
Example Output:
Mirrors are used for reflecting what?