[单项选择]需求的价格弹性是指( )。
A. 商品的需求量对商品本身价格变动的反应程度
B. 一种商品的需求量对于另外一种商品价格变动的反应程度
C. 商品的需求量对于消费者收入变动的反应程度
D. 由于影响供给的诸因素发生变化，供给量作出反应的程度

{{B}}The Risk of Tanning (日晒){{/B}}
This is just the time of year when the temptation to hit a tanning salon (沙龙) is highest, particularly for women, who make up an estimated 70 percent of tanning customers. With wedding season around the corner, and beach weekends not far off, a lot of women think they need some "healthy color" to look their best. But dermatologists (皮肤专家) say that there is no such thing as a healthy "real" tan. "A tan is essentially an injury to the skin," says Dr. Henry Lim, chairman of the department of dermatology at the Henry Ford Hospital in Detroit. "Tanning is just a reaction by the skin to try and protect itself."
While most people know they have to have sunscreen whenever they’re in the sun for more than a few minutes, there’s a lot of confusion about the relative merits and risks of tanning salons. Promoters say tanning machines are healthy because they emit mostly
A. To tell people the forbidden place where to get tanning.
B. To increase customers’ attention to the risk of Tanning.
C. To force manufacturers to make standard warning labels.
D. To warn people of the increased danger of get tanning.