The correct answer is: C. Fink truss
A Fink truss is a type of triangular truss that is commonly used in bridges and other structures. It is made up of vertical posts, diagonal members, and horizontal chords. The diagonal members are arranged in a zigzag pattern, which gives the truss its characteristic appearance.
The Fink truss is a statically determinate structure, which means that the forces in all of its members can be determined using simple statics principles. However, if the truss is subjected to a load that is not evenly distributed, the method of substitution may be required to determine the forces in all of the members.
The method of substitution is a technique that is used to solve for the forces in members of a truss that are not directly connected to the supports. To use this method, one first assumes that the force in the member in question is zero. Then, the forces in all of the other members of the truss are determined using simple statics principles. Once the forces in all of the other members are known, the force in the member in question can be calculated by considering the equilibrium of the entire truss.
The method of substitution is a relatively complex technique, and it is not always necessary to use it to determine the forces in all of the members of a Fink truss. However, if the truss is subjected to a load that is not evenly distributed, the method of substitution may be the only way to determine the forces in all of the members.
The other options are incorrect because they are all types of trusses that are statically determinate. This means that the forces in all of their members can be determined using simple statics principles.