题目内容：

    Some birds are masters of crime. That means these species steal food from other birds and get away with it. Scientists have long wondered what these birds have in common. A new study suggests that big body size does not predict bad behavior. Instead, it is the size of the birds' brains that matters most.

To learn more about what makes some birds tend towards a life of crime and how they steal food from other birds, scientists analyzed 856 published reports of thieves. Researcher Julie says she started the project after watching birds steal dry dog food out of unattended bowls. She read about some dramatic examples of thieves, including birds that steal food from others flying in midair or bending through the sky. She learned that members of some species disturb other birds until they spit up food in their mouth.

Families that steal also tend to eat fish, mice, and other vertebrates （脊椎动物） instead of just insects. These meatier （多肉的）meals are hard to catch, and they deliver lots of valuable calories, so they are attempting to steal.

Finally, birds that steal tend to have big brains in relation to their bodies. That may seem surprising, since human bullies （欺凌弱小者）are often thought to be stronger in size. But for birds, stealing isn't about strength. It takes a clever brain to get food out of another hungry bird's claws, especially if that bird is bigger than you are.

1.What is the key factor of the birds' stealing food?

A.Body size. B.Living environment.

C.Brain size. D.Strength.

2.What can we learn from the last paragraph?

A.Stealing birds are often stronger.

B.For birds, stealing is about cleverness and tricks.

C.Birds steal food only from those that are smaller in size.

D.Birds that steal have small brains for their bodies.

3.The best title for the passage can be .

A.Diet Habits of a Feather

B.Hunting Skills of a Feather

C.Brains of a Feather

D.Thieves of a Feather