题目内容：
Even plants can run a fever，especially when they’re under attack by insects or disease．But unlike humans，plants Can have their temperature taken from 3,000 feet away—straightup．A decade ago，adapting the infrared(红外线)scanning technology developed for militarypurposes and other satellites，physicist Stephen Paley came up with a quick way to take thetemperature of crops to determine which ones are under stress．The goal was to let farmers pre-cisely target pesticide(杀虫剂)spraying rather than rain poison on a whole field，which in-variably includes plants that don’t have pest(害虫)problems． Even better．Paley’s Remote Scanning Services Company could detect crop problems be-fore they became visible to the eye．Mounted on a plane flown at 3，000 feet at night，an infra-red scanner measured the heat emitted by crops．The data were transformed into a color-codemap showing where plants were running“fevers”．Farmers could then spot-spray，using 50 to70 percent less pesticide than they otherwise would．
The bad news is that Paley's company closed down in 1984，after only three years．Farm,ers resisted the new technology and long-term backers were hard to find．But with the renewedconcem about pesticides on produce，and refinements in infrared scanning，Paley hopes to getback into operation．Agriculture experts have no doubt the technology works．“This techniquecan be used on 75 percent of agricultural land in the United States"，says George Oerther ofTexas A&M．Ray Jackson，who recently retired from the Department of Agricuhrue，thinks re-mote infrared crop scanning could be adopted by the end of the decade．But only if Paley findsthe financial backing which he failed to obtain 10 years ago．
根据以上内容，回答题。
In order to apply pesticide spraying precisely，we call use infrared scanning to _________. A．locate the problem areas
B．drew a color-coded map
C．measure the size of the affected area
D．estimate the damage to the crops
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