Task: Question Answering
Input (English): A student sets a block at the top of a wooden ramp. The student pushes the block. As the block slides down the ramp, it slows down and then comes to a stop. What force causes the block to slow down?  
 (A) the force of gravity (B) the force of friction (C) the force of magnetism (D) the force of the student's push
Output (English): B