题目内容：

    The entire global population of marbled crayfish (龙纹虾) has been traced to a single female held in a German aquarium (水族馆), which was born with the ability to reproduce without males. Every marbled crayfish is female, and every egg laid is an exact clone of its mother. The ability to reproduce quickly with such ease made them popular in the aquarium trade, but when they found their way into the wild, the crayfish got out of control.

The first known marbled crayfish appeared in 1995. Since then, they have spread into the wild and populated in freshwater ecosystems around the world. Scientists studying this animal have raised the alarm about its likely influence on local wildlife, ecosystems and agriculture as it spreads into new environments. Successful non-native species like the marbled crayfish often cause trouble when they arrive in new environments, as they can feed on local wildlife or compete with it for resources.

According to Dr Frank Lyko, a researcher at the German Cancer Research Centre, the first marbled crayfish appeared due to a sudden change in its parents’ cells. It was an animal that reproduces clonally and therefore represents a model of a central aspect in tumor (肿瘤) development.

“Tumor genomes (基因组) also develop clonally, because they go back to a single original cell,” he said. However, both crayfish and tumors are still able to adapt to their environments through a process termed “clonal evolution”, and in both cases this can be harmful. In crayfish, their ability to adapt means they can spread to a variety of different environments and climates, and in tumors this means they can develop resistance (抵抗) against cancer-targeting drugs.

At present, with the potential influence of the increasing marbled crayfish on local places, governments from different places are working on controlling their population.

1.What does the text say about marbled crayfish in the wild?

A.They prove popular. B.They are under control.

C.They can be troublesome. D.They are out of condition.

2.What does Dr Frank Lyko try to explain?

A.The reason for marbled crayfish’s clonal reproduction.

B.The similarities between marbled crayfish and tumors.

C.The way to stop marbled crayfish cloning themselves.

D.The harmful influence marbled crayfish have on health.

3.What are governments doing about marbled crayfish now?

A.Working on removing all of them. B.Trying to limit the quantity of them.

C.Taking control of them with drugs. D.Connecting them with harmful tumors.

4.What can be a suitable title for the text?

A.Why Marbled Crayfish Reproduce Rapidly

B.The Population of Marbled Crayfish Is Huge

C.The Spread of Marbled Crayfish Is Worrying

D.How to Control the Number of Marbled Crayfish