题目内容：
根据材料，回答题。 The Gene Industry
Major companies are already in pursuit of commercial applications of the new biology. They dream of placing enzymes(酶) in the automobile to monitor exhausts and send data on pollution to a microprocessor(微处理机) that will then adjust the engine. They speak of what the New York Times calls "metal-hungry microbes(渴望吃金属的微生物）that might be used to mine valuable trace metals from ocean water". They have already demanded and won the right to patent newlifeforms.
Nervous critics, including many scientists, worry that there is corporate, national, international, and inter-scientifiC．rivalry in the entire biotechnological(生物工艺学) field. They create images not of oil spills, but of "microbe spills'" that could spread disease and destroy entire populations. The creation and accidental release of extremely poisonous microbes, however, is only one cause for alarm. Completely rational and respectable scientists are talking about possibilities that stagger the imagination.
Should we breed people with cow-like stomachs so they can digest grass and hay, thereby relieving the fOod problem by modifying us to eat lower down on the food chain? Should we biologically alter workers to fit the joB．requirement, for example, creating pilots with faster reaction times or assembly-line workers designed to do our monotonous work for us? Should we attempt to eliminate "inferior" people and breed a "super-race"? (Hitler tried this, but without the genetiC．weaponry that may soon issue from our laboratories. ) Should we produce soldiers to do our fighting? Should we use genetiC．forecasting to pre-el!minate "unfit" babies? Should we grow reserve organs for ourselves, each of us having, as it were, a "savings bank" full of spare kidneys, livers or hands?
Wild as these notions may sound, every one has its advocates (and opposers) in the scientifiC．community as well as its striking commercial application. As two critics of genetiC．engineering,Jeremy Rifkin and Ted Howard, state in their book Who Should Play God? "Broad scale genetiC．engineering will probably be introduced to _America much the same way as assembly lines, auto-mobiles, vaccines, computers and all the other technologies.. As each new genetiC．advance becomes commercially practical, a new consumer need will be exploited and a market for the new technology will be created. "
According to the passage, the exhaust from a car engine could probably be checked by A．using mtal-hungry microbes
B．making use of enzymes
C．adjusting the engine
D．patenting new lifeforms
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