题目内容：

    Two heads are better than one. After all, when trying to make decisions, it's good to have a second opinion. But what about a third, fourth — even twelfth? What group size is best for making decisions quickly? For ants, four to six heads surpass one ― and also outperform 12 or 24. That's what Sylvia Zamescu now reports.

The 18-year-old senior at Catalina Foothills High School in Tucson, Arizona isn't generally into ants. She's interested in decision-making, especially by people. Last summer, Sylvia read that social insects such as ants and bees can be used to model decision-making. Ants, for example, forage for food. When an ant finds it, it takes a bite and heads back to the nest. On the way; the ant leaves a scented trail for other ants to pick up. Back at the nest, the ant vomits up its meal into the mouth of other ants. Those nest-mates then decide with the first ant whether the food is good enough to deserve a trip back for more. If it is, they follow the first ant's scented trail to lunch.

When there are too few ants, it could take a long time for one ant to spread the word If there are too many, it's hard to “tell" each about the find. What's the right number for foraging success? Sylvia decided to find out. She contacted professors at the University of Arizona in Tucson to look for someone who would let her study decision-making by ants in their lab. Professor Wulfila Gronenberg answered her email.

Working with one of Wulfila's graduate students, Sylvia set up an experiment She tested the behavior of one, two, four, six, twelve and twenty-four ants. Each group was placed in a large box al taped "starting line". At the other end of the box were two bricks of sweetened gelatin （动物胶） one contained only 3 per cent sugar, and the other 30 per cent. Sylvia timed how long it took each group of ants to find the food. She also measured how much time they spent around each sweet treat.

When there were just one or two ants, the discovery was slow. The same was true when she set twelve or twenty-four ants loose. But four to six ants? Perfect! These medium-size groups found the food forest. They also figured out quickly that the sweeter food was better.

Similar work has been done on bighorn sheep, fish and fruit flies. "It may not be four to six animals, but it's the same principle," Sylvia says. A medium-size group "is optimal". So when faced with a new decision, two heads are better than one. But too many heads are too much. Like the ants, a good decision may just require a happy medium.

1.What gave Sylvia the idea for her research?

A.Her interest in social insects.

B.An article about social animals.

C.A university professor's invitation.

D.Her doubt about a science report.

2.What do we know about Sylvia's experiment?

A.She set it up with Professor Wulfila Gronenberg.

B.There were two large boxes at the "starting line".

C.There were several kinds of foods for the ants.

D.She divided the ants into six different groups.

3.What did Sylvia find out about ants?

A.They make decisions faster in medium-sized groups.

B.They are better at finding food in smaller groups.

C.They perform much more smartly in larger groups.

D.They make better decisions when working together.