Given scientific fact as input, generate the question from this fact such that it can be answered from the input.

Example Input: Skeletal muscles must work in pairs to move bones back and forth at a joint because they can only contract.
Example Output: Skeletal muscles must work in pairs to move bones back and forth at a joint because they can only do what?

Example Input: Under a crushed sugar cube is added and the water is stirred conditions would a sugar cube dissolve most quickly when placed in a liter of water at room temperature.
Example Output: Under which conditions would a sugar cube dissolve most quickly when placed in a liter of water at room temperature?

Example Input: 40 m/s north of the following represents the velocity of a moving object.
Example Output:
Which of the following represents the velocity of a moving object?