a) the process of making holes in the structure
b) process of making mould for structure
c) method of joining together pieces of metal by inserting ductile metal pins called rivets
d) method of joining together pieces of metal by inserting non ductile metal pins called rivets

Answer: c
Explanation: Riveting is the method of joining together pieces of metal by inserting ductile metal pins called rivets into holes of pieces to be connected and forming a head at end of rivet to prevent each metal piece from coming out.