What are the advantages of CNG over petrol?

The advantages of CNG (compressed natural gas ) over petrol are:

1.     CNG is a cleaner fuel as it is less polluting.

2.     It burns without producing smoke.

3.     It can be easily transported through pipes.

4.     It can also be used directly at homes and factories for burning.

5.     It is cheaper than petrol.

6.     The ignition temperature of CNG is double the ignition temperature of petrol. Thus, it is less likely to catch fire in case of leakage.

Hence, among the all options, "It is less polluting" is correct.