Which of the following pairs are correctly matched?
1. Lead screw nut…. Phosphur bronze
2. Piston…. Cast iron
3. Cam…En-31 steel
4. Lead screw…wrought iron
Select the correct answer using the codes given below
(a) 2, 3 and 4 (b) 1, 3 and 4
(c) 1, 2 and 4 (d) 1, 2 and 3