The Main Problem with Use of Conventional Natural Gas as a Transportation

Multiple Choice

The main problem with use of conventional natural gas as a transportation fuel is

A) the expensive engine modifications required to convert an automobile for use of natural gas
B) the fact that it has higher CO₂ emissions than gasoline produced from conventional oil
C) the very low reserves, which could supply U.S. needs for less than 25 years
D) the fact that not many fueling stations exist at present
E) it can only be obtained by fracking