Consider the following statements:
1. Pulverized fuel gives high and controlled burring rate.
2. Insufficient air causes excessive smoking of exhaust.
3. Excess air is provided to control the flue gas temperature.
4. Effect of sulphur in fuel is to give high heat transfer rate.
Which of these statements are correct?
(a) 3 and 4 (b) 2 and 3
(c)1 and 2 (d) 1 and 4