She’s not afraid of anything. Snakes? No problem. Walking alone in the dark? Easy. We’re not talking about a superhero here -- SM is a 44-year-old mother.  And she’s fearless because she happens to be missing part of her brain: the amygdala(扁桃腺).
Shaped like a pair of almonds sitting in the middle of your brain, the amygdala helps control fear and anxiety. A rare condition called Urbach-Wiethe disease left SM without her amygdala, and seems to have completely erased her sense of fear.
To try to understand how the amygdala works, a team of researchers made their efforts to scare SM. They showed her horror movies and took her to the Waverly Hills Sanatorium Haunted House in Kentucky. She pushed out one of the monsters(巨物) and laughed. SM said she didn’t like snakes, but at a pet store full of poisonous creatures, she kept asking to touch them. When asked to rate her feelings, SM reported feeling surprised or disgusted, but never fearful.
“She tends to approach everything she should be avoiding,” says Justin Feinstein of the  University of Iowa. This means the amygdala could control deeper urges to approach or avoid danger. Other scientists have a different opinion, though.  “I don’t believe you can make a general statement about what the amygdala does by a single case study,” Elizabeth Phelps said. In 2002, Phelps published a study on a similar patient with amygdala damage who still showed fear.
It may sound like fun to be totally fearless, but we get scared for a good reason. “The nature of fear is survival and the amygdala helps us stay alive by avoiding situations, people, or objects that put our life in danger,” Feinstein said. SM was once followed in a park after dark by a man with a knife, and she simply walked away. “It is quite remarkable that she is still alive,” said Feinstein.
SM dares to walk alone in the dark mainly because ____________.

A．she is a superhero

B．she has experienced such conditions a lot

C．she is a mental patient

D．she has no sense of fear

Researchers tried their best to frighten SM in order to find ___________.

A．The function of a particular organ

B．SM’s reaction of fear and anxiety

C．The process of removing amygdale

D．A special way to get along with monsters

What do we know from the research on SM?

A．It was easy for her to avoid danger.

B．SM never felt fearful but disgusted.

C．SM was frightened by nothing except monsters.

D．SM got along well with the snakes.

What is Elizabeth Phelps’ attitude toward the function of the amygdala based on the research on SM?

A．Indifferent

B．Supportive

C．Disapproving

D．Interested

What can we infer from the last paragraph?

A．People can remove their amygdala to be fearless.

B．SM will be admired because of her bravery.

C．No one can survive if their amygdala is removed.

D．The sense of fear is crucial to humans.