单项选择题

Did Grandma seem forgetful at the holiday parties last month It could be time to put her on a diet. Sharply (67) calories(卡路里) improves memory in older adults,according to a new study.
Research on the benefits of an extremely low-calorie diet (68) back to the 1930s, when scientists found that rats lived (69) to twice as long when they ate less than control animals. And how about in human To fill that (70) , scientist Agnes
and her colleagues at the University of Muenster (71) 50 healthy elderly subjects. The (72) volunteer was 60 years old and overweight. The researchers (73) assigned the volunteers to one of three groups. Twenty people were instructed to reduce their daily calorie (74) by 30%, while still eating a (75) diet. Another 20 were told to keep their calorie intake the same but increase their (76) of unsaturated(不饱和的 ) fatty acids. The (77) 10 volunteers did not change their diets.
After 3 months, all of the volunteers (78) a memory test in which they were shown 15 words and asked how many they could remember after 30 minutes. (79) average,those in the calorie-restriction group showed a 20% (80) over their baseline memory scores taken before they started their diets. Subjects in the other two groups showed (81) or no improvement. "Our study (82) provides some of the first (83) on the impact of calorie restriction on memory in the elderly, but this study has to be (84) up now," Floel noted. Her team plans to (85) larger studies to determine exactly (86) calorie restriction enhances memory.