Three weeks after delivery of a unilateral distal extension mandibular removable partial denture, a Pt complained of a sensitive abutment tooth, clinical examination reveals sensitivity to percussion of the tooth

Three weeks after delivery of a unilateral distal extension mandibular removable partial denture, a Pt complained of a sensitive abutment tooth, clinical examination reveals sensitivity to percussion of the tooth, the most likely cause is:

a. Defective occlusion.***

b. Exposed dentine at the bottom of the occlusal rest seats.

c. Galvanic action between the framework and an amalgam restoration in the abutment tooth.