They already guide blind and disabled people; now dogs are to be trained to help people with dementia（痴呆） or Alzheimer's．Alzheimer's can make people confuse night and day or forget basic things such as washing or drinking enough water．
The dogs will be trained to respond to sound triggers（触发器） in the home that cause them to perform tasks．The duties will include reminding their owners to take medicine, as well as encouraging them to eat, drink and sleep regularly．
The idea was developed by design students at the Glasgow School of Art and will now be put into practice by Alzheimer's Scotland and Dogs for the Disabled．The first dogs will be distributed to four Scottish couples, where one of the partners is in the early stages of dementia．Some 670,000 people in Britain have dementia and one in three over 65s will develop the condition．By 2021 this is expected to rise to one million．
Joyce Gray of Alzheimer's Scotland said, "People in the early stages of dementia are still able to live a relatively normal life, and dogs help to maintain routine．" Another advantage of using the pets as companions is that dogs can give them a sense of silent support and companionship．Ms Gray said, "The evidence is that people may forget familiar faces but not pets．It's such a strong bond that people often remember them longest．People don't need to communicate verbally （言语地） but they can still interact．You can have a speechless bond．"
Helen McCain, director of Dogs for the Disabled, said, "People with dementia often forget to take the medicine．If a dog presents them with a bag with pills in it there's a greater chance of them taking it．The dog would also encourage the owner to take them out for walks, ensuring they keep exercising and interacting with other people．"
In Britain people with dementia _          _．

A．are likely to increase in number

B．are mostly over 65 years old

C．will be trained to respond to sound triggers

D．will be able to live a relatively normal life

The dogs are taught to perform tasks by -．

A．making some sound signals

B．communicating with the patients

C．reminding the patients by barking

D．reacting to some sound triggers

What does the underlined word "them" in Paragraph 4 refer to?

A．Faces．

B．Triggers．

C．Pets．

D．Companions．

What is mainly talked about in the passage?

A．The idea of dementia dogs was developed by students．

B．Dogs are trained to assist Alzheimer's patients．

C．British people with Alzheimer's are in poor condition．

D．The dementia dogs perform most duties of a doctor．