A、They have difficulty in storing new memories. B、They seldom get irritated. C、They are eager to be involved in the society. D、T

　　When it comes to aging, life can be cruel. There’s plenty to think about. What will happen to my looks? Will I still be able to pursue my interests? (16) What will happen to my mind? That last question is now the second leading health concern, after cancer, among adults in at least four Western countries—France, Germany, and Spain, as well as the United States—according to a recent survey by Harvard University. Fear of developing Alzheimer’s would likely stir even more concern if Americans didn’t mistakenly believe a cure for the disease exists. As the sixth leading cause of death in the US, (17) Alzheimer’s disease is marked by difficulty storing new memories and recalling recent events, loss of ability to track day-to-day information, a disrupted sense of time and space, social withdrawal, irritability and mood swings. Life expectancy in the US is currently about 78 years and rising. The 5.4 million Americans who suffer from the illness include 13 percent of those over age 65. (18) The vast majority of Alzheimer’s cases—over 99 percent—are not linked to genetic factors. But they are linked to obesity. Researchers find that the same lifestyle choices that lead people to become obese or develop heart disease also increase the risk of developing Alzheimers. Choices we make throughout life about what we put in our bodies may protect against Alzheimer’s, or delay its onest. Heading off the disease starts with what we eat. Everything we consume prompts a reaction in the brain. (19) Picking the right foods can minimize damage to neurons and preserve a healthy mind as you age.
　　16. What is the first health concern when people become old according to the survey?
　　17. What do we know about people with Alzheimer’s disease?
　　18. What is the root cause of Alzheimer’s according to the researchers?
　　19. What is suggested in the passage to keep a healthy mind?