Consider the following statements regarding otto cycle:
1. it is not a reversible cycle.
2. Its efficiency can be improved by using a working fluid of higher valuve of ratio of specific heats.
3. The practical way of increasing its efficiency is to increases the compression ratio.
4. Carburetted gasoline engines working on otto cycle can work with compression ratios more than 12.
Which of these statements are correct?
(a) 1,3 and 4 (b)1,2 and 3
(c)1,2 and 4 (d) 2,3 and 4