Here's a problem to solve: A student measures the acceleration of a stone block on a level surface when the block is acted upon by a known force. What additional information is needed to precisely calculate the block's mass?

Among the 4 following options, which is the correct answer?

- A: the block's density
 
- B: the amount of friction
 
- C: the mass of the surface
 
- D: the direction of motion
 