IMO A

IMO B since environmentalists are already convinced about the ecological benefits of ethanol and are really not bothered about other pollutants hence A is eliminated.
If ethanol is lets say 20 times more expensive than gasolilne,will it be considered as an alternate? i doubt so B

A is too extreme as it says"... does not release any pollutants"
hence B or D
IMO D

IMO A because although ethanol produces less cabon monoxide,it could still pollute more than other available fuel sources if it contains any other pollutants.A closes the hole

a. When burned as fuel, ethanol does not release any pollutants at higher levels than does gasoline.
b. Ethanol is comparable in price to gasoline.- pollution not price is the consideration

c. Available supplies of corn are sufficient to supply several years' worth of ethanol. out of scope as if there are not enough supplies of corn,It can be harvested more if required.

d. Most gasoline companies already possess the technology to produce - ethanol. - if the technogy is not widely avaiable,it could be made avaiable in the future - out of scope

e. Ethanol can be used as heating fuel.- out of scope.the ques is not about ethanol as a fuel used for heating

A is the right answer as it says about the other pollutants as well. hence supports the argument.
other answer choices are irrelevant.

My Answer is A.

All other choices are irrelevant.

Thanks
Raama

IMO C

IMO A.

the scope the environmentalists' argument is that ethanol is less polluting, not that it is generally better than gas.

As a side note, ethanol really isn't all that great because it requires lots of energy (from oil) to create, and uses valuable farm land that drives up the price of crops.

Conclusion

ethanol is a better source of energy than gasoline.

Reason:

it emits significantly lower levels of carbon monoxide, a major atmospheric pollutant

b. Ethanol is comparable in price to gasoline.

Price= out of scope

c. Available supplies of corn are sufficient to supply several years' worth of ethanol

Concerned point is Pollutants and not supplies

d. Most gasoline companies already possess the technology to produce ethanol.
e. Ethanol can be used as heating fuel.

Again both out of scope

only A discusses about Pollutants. although not the best answer because of extreme word as pointed out in the previous post. But still A is best among the given choices

Hope this Helps

It seems to me that the right answer is A