阅读下面短文，从各题A、B、C、D四个选项中，选出最佳答案。
People who smoke could lose around one third of their daily memory, researchers say.
A study by a team at Northumbria University showed that smokers lost more of their memory when compared to non-smokers.
And the research also found that those who kicked the habit saw their ability to recollect information restored to almost the same level as non-smokers.
The study involved more than seventy 18-to-25-year-olds and included a tour of the university’s campus. Those who took part were asked to recall small details, such as a list of songs played at a campus concert and tasks completed at various points－known as real world memory test. Smokers performed badly, remembering just 59 percent of tasks. But those who had given up smoking remembered 74 percent and those who had never smoked recalled 81 percent of tasks.
Dr. Tom Heffernan, who leads Northumbria University’s Collaboration for Drug and Alcohol Research Group, said the findings would be useful in anti-smoking campaigns. He said, “Given that there are up to 10 million smokers in the UK and as many as 45 million in the United States, it's important to understand the effects smoking has on everyday cognitive（认知的）function-of which prospective memory is an excellent example. ”
“This is the first time that a study has set out to examine whether giving up smoking has an impact on memory. We already know that giving up smoking has huge health benefits for the body, but this study also shows how stopping smoking can have knock-on benefits for cognitive functions too. ’’
The research will now investigate the effects of passive smoking on memory, while Dr. Heffernan and Dr. Terence O’Neil will look into the effects of third-hand smoking－toxins left on curtains and furniture.
What’s the main idea of the passage?

A．Smoking does harm to health.

B．Smokers take a tour to the University’s campus.

C．Smoking can affect one’s memory.

D．Smokers are compared to non-smokers.

How did those who took part in the study perform when asked to recall small details?

A．Smokers did the worst among the participants.

B．Non-smokers could recall about half of them.

C．Smokers could recall nothing at all.

D．Those who gave up smoking did best.

According to Dr. Tom Heffernan, the findings_______.

A．would be really a surprise to the public

B．would contribute to fighting against smoking

C．would be used in real world memory test

D．would be nothing new to the researchers

What does the underlined word “impact’’ most probably mean?

A．order

B．impression

C．expression

D．effect

What will Dr. Heffernan and Dr Terence O’Neil do?

A．Investigate the effects of third-hand smoking.

B．Do research on how smoking affects passive smokers.

C．Find ways to persuade people to quit smoking.

D．Study whether giving up smoking affects memory.