Ocean sounds may help people sleep at night,but marine animals depend on them for survival.For example,dolphins rely on echolocation to hunt and communicate with their companions.Such species are in trouble,because human generated ocean noise has increased significantly since the Industrial Revolution.
Ships alone always generate low-frequency volume along shipping routes by an estimated 32 times.That along with tones from sonar,seismic surveys,pile driving,and even motorboats,all of which can be heard easily by marine animals in the water,can trap whales in ice by delaying their migration,according to a review published last week in Science.
The paper notes that climate change also threatens the sound track of the sea.The Great Barrier Reef has quieted over the years,but it has become smaller in size and become less habitable because of climate change.Animals that rely on the sounds of coral reefs to locate food and settlements may struggle to adapt.
Earlier this year,whale scientist and National Geographic Explorer Jansen Greenwood found an unusual scene.He returned from studying whales in Antarctica to find few cars on the road,virtually no ships on the sea,and humpbacks arriving at one of the Golden State's most popular coastal recreation spots from their winter habitats in Mexico.He believed the reason may be that the place was suddenly free of the human noises.
The experts argue that making the sea quiet should be a core component of environmental policy.And they say it can be done：A study conducted at the start of the COVID-19 pandemic,for example,found that a reduction in shipping traffic coincided with an average decrease of 1.5 decibels in waters along shipping routes near the Port of Vancouver.



What does paragraph 2 mainly talk about？ ______

A. The research on ships.
B. The major threat to whales.
C. The popularity of shipping.
D. The harm of ocean noise.

What does the author intend to do in paragraph 3？ ______

A. Add more relative information.
B. Introduce a new topic for discussion.
C. Provide some advice for the renders
D. Summarize the previous paragraphs.

Why did the humpbacks arrive at the recreation spot according to Jansen？ ______

A. It became quiet.
B. It was their winter habitat.
C. They wanted to look for food.
D. They adapted to climate change.

What should environmental policy focus on？ ______

A. Producing fewer ships.
B. Reducing ocean noise.
C. Changing shipping routes.
D. Stopping human activity.