Which simple machine can be used to split a log?
(A) fulcrum
(B) pulley
(C) level
(D) wedge

Hint
We know the meaning of mechanical advantage. Mechanical advantage is a measurement of how much a simple machine multiplies a force. We know that the mechanical advantage is greater than 1 for wedge. So, the wedge is used to split the log.

Complete step by step answer
A wedge is a simple machine that consists of two inclined planes, giving it a thin end and thick end. A wedge is used to cut or split apart objects. Force is applied to the thick end of the wedge, and the wedge, in turn, applies force to the object along both of its sloping sides. This force causes the object to split apart.
A mechanical advantage is a form of calculation that measures the amplified force taken by the mechanical system. It is the ratio between the force applied to the load and the force needed to overcome the given force.
  $ MA\,\, = \dfrac{{{F_B}}}{{{F_A}}} $
MA= the mechanical advantage, $ {F_B} = $ force of the object and $ {F_A} = $ effort to overcome the force of the object.
A wedge applies more force to the object (output force) than the user applies to the wedge (input force), so the mechanical advantage of a wedge is greater than 1. A longer, thinner wedge has a greater mechanical advantage than a shorter, wider wedge.
For wedge $ MA > 1 $
Hence the required solution is wedge is used to split a log (option ‘D’).

Note
A pulley is a simple collection of one or more wheels over which one can make a loop to lift things in an easier way. So, pulley is not used to split a log. The mechanical advantage plays an important role for splitting the log. Fulcrum is a pivot point around which the liver turns. So, option ‘A’,’B’ and ’C’ are not true.