GMAT Critical Reasoning (CR) | Re: Company spokesperson: In lieu of redesigning our plants

Company spokesperson: In lieu of redesigning our plants, our company recently launched an environmental protection campaign to buy and dispose of old cars, which are generally highly pollutive. Our plants account for just 4 percent of the local air pollution, while automobiles that predate 1980 account for 30 percent. Clearly, we will reduce air pollution more by buying old cars than we would by redesigning our plants.

Which one of the following, if true, most seriously weakens the company spokesperson’s argument?