73. According to the passage, which of the following statements is true?
(A) Many studies have found that low-calorie diets improve elderly people’s memory.
(B) Low-calorie diets extend a mouse’s life to 70 years.
(C) Low-calorie diets benefit both animals and humans.
(D) In Witte’s experiment, volunteers got dieticians’ advice and a phone call on a dailybasis.