A
Acetabular shell and polyethylene liner
B
Femoral stem and cement mantle
C
Modular femoral head and femoral stem neck taper
D
Acetabular shell and pelvic subchondral bone
Explanation:Correct Option: C. Trunnionosis (or taperosis) refers to the adverse local tissue reactions caused by fretting and mechanically assisted crevice corrosion specifically at the Morse taper junction between the modular femoral head and the femoral stem neck (the trunnion). (Ref: Jacobs et al., J Bone Joint Surg Am, 1998)