题目内容：
回答题。To find Kim Hyung Gyoon's office in Samsung's R&D complex, just follow the baskets of dirty clothes. No, Kim is not running the company laundry. As chief of Samsung's Washing & Cleaning Technology Group (WCTG), he's the man behind a new washing machine that deposit tiny silver particles (small pieces of things)--about l/10,000 the thickness of a human hair—onto clothes to make them germ-and-odor-free without the need for hot water. The device represents the first mass-produced application of this type of nanotechnology--the science of very small structures--to home appliances. "In summer of 2002, I asked everyone in the office to take off the socks," says Kim."I took one sock from each person and placed it in a regular washing machine; the others were washed in a machine with the Ag+ Nano System. The next day, I asked everyone to check the odor of their socks after a day's wear. One began to produce a strong unpleasant smell, and the other was odorless."
Kim says he came up with the idea five years ago while on a business trip to Japan, where he learned of a brand of socks that retained their freshness even after many days of unwashed wear and tear. Tiny sticks of silver with germ-killing chemicals were woven into the fabric. When he go back to Seoul, Kim applied the principle to washing machines.
According to the Korea Testing & Research Institute for the Chemical Industry, Samsung's device kills 99.9% of germs. Kim says garments stay germ-free for up to a month after being laundered. The Ag+ Nano device went on sale in March 2003 and costs around $1,150; the revolutionary technology is also being used in Samsung's refrigerators and air conditioners.
No wonder: consumers seem to like a little silver in their spin cycles. Since Samsung's nanoarmed products were first launched, they have brought in an estimated $ 779 million in revenue. Overall, nanotech has been one of science's fastest-growing fields in recent years, with potential applications in fields as diverse as energy production and toothpaste manufacture. The nanotech market is projected to be worth $1 trillion by 2015.
Which of the following best describes the nature of Kim Hyung Gyoon's work? A．Product development.
B．Market investigation.
C．Research designing.
D．Sales promotion.
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