A、They are threatening the sea life in the area. B、They are diversifying its marine environment. C、They are simplifying the food

Lionfish are known for their beauty and unusual look. But lionfish are also poisonous, with extremely long and separated spines to carry and shoot poison. The native environment for lionfish includes the South Pacific and Indian Ocean.
    However, sea experts say lionfish were at some time released into the Atlantic Ocean, likely by people who had kept them in tanks. Lionfish are currently considered a great threat to coral reefs and related sea life in coastal waters of the southeastern United States and Caribbean.
    Scientists say the fish is a top predator that competes for food and space with native fish in the area. Now there is a new solution for fighting back.
    University researchers are developing an underwater robot to hunt down, kill and collect lionfish.
    A student-led team at Worcester Polytechnic Institute in Massachusetts developed the robot. The team recently demonstrated the device and is continuing to test and make changes to it.
    The team says that the robot is designed to recognize the lionfish, chase it and shoot the animal with a spear, which then separates from the robot and floats the fish to the surface for collection. Craig Putnam is a computer science professor at Worcester Polytechnic Institute and a director of the school’s Robotics Engineering Program. He says the robot was built to simplify the process of hunting down and collecting this aggressive fish.
    Putnam said his team trained the robot system by showing it thousands of images of lionfish in different colours, from many directions and under different lighting conditions. The robot can correctly identify lionfish about 95% of the time, he added.
    Questions 12 to 15 are based on the passage you have just heard.
    12. What does the speaker say about lionfish?
    13. What are lionfish doing to the Atlantic Ocean?
    14. What can we learn about the team that developed the robot?
    15. How did the team train the robot system to hunt down the lionfish?