Elbow joint is an example of

The movement of the Elbow is restricted to only in one plane..

It can be understood well with the example of a door where the door is  is joined at a hinge and movement occurs only in one direction.

Two ones of ebow are joined together just like hinge of the door

It facilitates movement only in one plane.

Thus, the elbow is an example of a hinge joint.

Option A is the correct answer, i.e. elbow is an example of hinge joint.