Answer : (D) Fulcrum.
Explanation :
It is given that Julian stands on his toes to lift his body high enough so that he can reach a book. This is the example of a second class lever.
In the second class lever, the load is between the effort and the fulcrum.
In this case, the muscles provide the input force. His weight of the foot that is lifted up is the output force and toes act as a fulcrum.
So, the correct option is (D) Fulcrum.