The balls of the ball bearings are manufactured from steel rods. The operations involved are
1. Ground
2. Hot forged on hammers
3. Heat treated
4. Polished
What is the correct sequence of the above operations from start?
(a) 3-2-4-1 (b) 3-2-1-4
(c) 2-3-1-4 (d) 2-3-4-1