The correct answer is: A. Method of joint.
The graphical method of determining the forces in the members of a truss is based on the method of joint. This method involves drawing a free-body diagram of each joint in the truss and then solving for the unknown forces using the laws of statics.
The method of section is a different method for determining the forces in the members of a truss. This method involves cutting through the truss at a section and then drawing a free-body diagram of the portion of the truss that is on one side of the section. The unknown forces in the members of the truss can then be solved for using the laws of statics.
Neither method is based on the other.