题目内容：
根据材料，完成题。第一篇
Optimism
Ever won the lottery? No? But did that stop you buying another lottery ticket? If the answer is another "no", you might call yourself an optimist.
According to researchers at University College London, human beings are sanguine creatures. It is all in the brain, they say. A study suggests that human brain is very efficient at processing good news: about 80% of people have a tendency to see the glasses half-full, not half-empty, even if they don't consider themselves to be optimists.
The good news is that this brings a health benefit. Having a positive outlook on life reduces anxiety. A study of nearly 100, 000 women showed a lower risk of death from heart disease among optimists.
But there are problems in always having an optimistic attitude. The authors of the study point out that the 2008 financial crisis may have been caused by analysts overestmafing their assets' performance even in the face of clear evidence to the contrary.
There are personal health risks too. Dr Tali Sharot, lead researcher, said: " Smoking Kills' messages don't work since people think their chances of cancer are low. There's a very fundamental tendency in the brain. "
But, as they say, every cloud has a silver lining. Even if seeing the world through rose-colored glasses poses a risk to our health, it's not something that is likely to cause us to lose sleep. Let's just keep our chins up and keep smiling!
What does "sanguine" (Para. 2) mean?__________. A．depressed
B．cheerful
C．lucky
D．emotional
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