单项选择题

Passage Four
They are unnecessary but wanting them seems to be part of human nature. Cosmetics are any preparation applied externally to the body so as to condition, beautify, and protect it. Annual sales of cosmetics in America, mostly to women, are approaching 20 billion dollars a year—four times more than the entire motion picture industry makes. Worldwide, cosmetics sales are estimated at four times the U. S. total. Of the estimated 1,000 registered cosmetics companies, nearly a third of the sales are by the top three. Avon, Revlon, and Estee Lauder; 55 percent by the top eight.
Cosmetics fall into six categories. The top category is makeup, cosmetics for the face and eyes, having sales of about 6 billion dollars a year. The trend is for makeup that is good for the skin, and the "look" swings from natural and earthy to the fantastiC. Women’s hair care products are the second biggest category, at about 4.5 billion dollars a year. This market remains strong thanks to specialization-products for oily hair, dandruff, color-treated hair, and so on. Skin-care products are a close third at 4.3 billion a year. This category is growing as the population ages. Although studies show that simple ingredients such as lanolin and petroleum jelly produce beneficial results, marketers keep introducing new "improved" products. The fourth largest category, women’s fragrances, have yearly sales of 4.1 billion dollars. Fragrances employ sensational advertising to generate a feeling of excitement, glamour, and sex. In contrast, the fifth largest segment, personal cleanliness products at 3.9 billion a year, has a dull image. The smallest market, just a billion dollars a year, is men’s toiletries. Experts keep predicting this category will boom, but it has not happened.

According to the passage, hair care products（）

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