Given the question: Read the article and select the best answer. Article: Researchers claimed that waitresses who wear red get up to 26 percent extra in tips than they would wearing other colors. However, the team finds that the sexes tip very differently--with the bigger tips coming only from male customers. No matter what color they wear, female diners will give the same kind of amounts for service every time. Yet men, whether they realize it or not, add anything between 15 and 26 percent more to a waitress in red than they would if it was the same waitress wearing a different color. The test was simple. Take 11 waitresses in five restaurants over a six-week period and ask them to wear the same kind of T-shirt every day but change the colors. Previous research has suggested waitresses could earn more if they acted charmingly or wore more make-up than their colleagues. But this study, by the Journal of Hospitality and Tourism Research, only changed the color of the T-shirt. Every other aspect from make-up to behavior remained the same. When wearing either black, white, green, blue or yellow T-shirts, the size of the tips from both male and female customers was almost _ . But when they wore red, the size of the tips went up by between 15 and 26 percent from male customers, yet stayed the same from female ones. A total of 272 restaurant customers were studied by researchers Nicolas Gueguen and Celine Jacob for the international journal of the tourism industry. Even as a T-shirt, it shows just how much the color red is thought, by men, to increase the physical and sexual attractiveness of woman, said the researchers. The researchers wrote: As red color has no negative effect on women customers, it could be in their interest to wear clothes at work. Question: According to the passage, in the research by the Journal of Hospitality and Tourism Research waitresses could earn more by _ . Options: A: wearing red T-shirts B: putting on attractive make-up C: changing the color of T-shirts D: behaving themselves
The answer is:
A