Consider the following processes of gear manufacture
1. Milling with form cutter
2. Rack type gear shaper (gear planer)
3. Rotary gear shaper (gear shaper)
4. Gear hobbing
The correct sequence of these processes in increasing order of accuracy of convolute profile of the gear is
(a) 3,2,4,1 (b) 2,3,4,1
(c) 3,2,1,4 (d) 2,3,1,4