Consider the following operations involved in forging a hexagonal bolt from a round bar stock, whose diameter is equal to the bolt diameter
1. Flattening 2. Upsetting
3. Swaging 4. Cambering
The correct sequence of these operations is
(a) 1,2,3,4 (b) 2,3,4,1
(c) 2,1,3,4 (d) 3,2,1,4