Explanation:
In civil engineering, compression members are structural elements that primarily carry axial compressive loads. These members are designed to resist compressive forces and are typically found in various structural systems such as buildings, bridges, and towers. The given options are:

a) Strut: A strut is a compression member that is used to resist longitudinal compression forces. It is a slender structural component that is commonly found in trusses and bracing systems. Struts are designed to carry compressive loads and transfer them to the supporting structure.

b) Tie: A tie is not a compression member. It is a structural element that primarily carries tensile forces. Ties are used to resist pulling forces and are commonly found in tension members such as cables, ropes, and rods. They are designed to transfer tensile forces and maintain structural stability.

c) Rafter: A rafter is a compression member commonly found in roof structures. It is designed to carry vertical loads from the roof and transfer them to the supporting walls or columns. Rafters are subjected to compressive forces due to the weight of the roof and any additional loads.

d) Boom: A boom is a compression member used in structures such as cranes, derricks, and telescopic arms. It is designed to resist compressive forces and provide stability and support. Booms typically carry loads and transfer them to the base or supporting structure.

The correct answer is option 'B' (Tie). Ties are not compression members but rather tension members. They are designed to carry tensile forces and resist pulling forces, unlike compression members that primarily carry axial compressive loads.