单项选择题

TEXT D
Dear Sir,
After reading some of the letters printed in this newspaper, I’m beginning to believe that the carbon monoxide in this city’s air during the past year has already affected some people’s ability to think straight.
The proposal for limiting the use of ears seems fair and reasonable to me. I can’t feel that it will produce any real suffering on the part of motorists, who sometimes seem to put their rights to drive above the public’s right to breathe.
Surely everyone understand that it would be worse to have to wear gas masks in our city than to ride buses or trains. After all, breathing is necessary, and we might all breathe more easily ff we could reduce the amount of pollution in our air,
In writing this letter the author is ______.