In the context of proposals to the use of hydrogen-enriched CNG (H-CNG) as fuel for buses in public transport,
consider the following statements:
The main advantage of the use of H-CNG is the elimination of carbon monoxide emissions.
H-CNG as fuel reduces carbon dioxide and hydrocarbon emissions.
Hydrogen up to one-fifth by volume can be blended with CNG as fuel for buses.
H-CNG makes the fuel less expensive than CNG.
Which of the statements given above is/are correct?
a. 1 only
b. 2 and 3 only
c. 4 only
d. 1, 2, 3 and 4