题目内容：

The world's first-known nursery for baby giant manta rays(蝠鲼) has been discovered hidden away in the Gulf of Mexico, the place of 70 miles off the coast of Texas, after studying decades of giant manta ray data from the area by the scientists.

Where the baby manta rays grow up has long troubled scientists, as they are rarely spotted in the four to five years it takes them to become adults, when they can often grow to more than 20ft wide.

In the study Mr Stewart and colleagues describe a reef (暗礁)---filled with mantas of all ages---where the sea floor runs down into deeper water. He said "We think they may be feeding on specific types of zooplankton(浮游生物) there, then migrating up toward the surface, where we saw them. They might be hanging around the banks because it could be a little safer than open water. We’ve seen them so rarely that we know very little about these baby manta rays. We don‘t know how far they move, or exactly what they feed on, or all of the habitats these access.”

Giant manta rays are listed as species dying out by protectors, although actual population numbers of the mysterious "gentle giant" are hard to calculate. Sightings of the closely-related reef manta, however, have dropped by 90 percent in regions of southeast Asia in the past decade, according to a study.

Fishing is considered the biggest threat to giant manta numbers, both intentional and accidental. Their gill plates(腮下肉)- the parts through which they filter(过滤) their food from seawater-are sold in China for medical purposes, while they often end up as something caught by mistake due to their huge wings.

1.Where do the baby manta rays probably grow up according to the study?

A. In the deep water area.

B. On the surface of the sea water.

C. Around the banks of channel.

D. In the reef of the Gulf of Mexico.

2.What can we learn from Paragraph3?

A. Manta rays can be seen on the sea surface.

B. Manta rays prefer the open water to the banks.

C. The scientists have known much about manta rays.

D. Manta rays are fond of eating on the sea surface.

3.What is the main reason for the decrease of giant manta rays?

A. The habitat environment becomes worse.

B. They are overfished by people

C. They are not very difficult to catch.

D. People can see the reef manta much less than before.

4.What does the author intend to do in the last paragraph?

A. Summarize the previous paragraphs.

B. Warn people of their wrong behaviors.

C. Introduce some knowledge of the fish.

D. Give examples to support his point.