Question

read the passage.
saving sea turtles
small - scale fishing performed with nets is one of the most common fishing methods used around the world. one of the unfortunate side effects of this method is that sea turtles, which are considered threatened, get caught in the nets along with the fish. conservation biologists at the university of exeter in england recently devised a way to prevent these sea turtle deaths, which they tested at a fishery in northern peru. they found that attaching green led lights to the nets warned the turtles away, possibly because the lights made the nets more visible. the number of sea turtle deaths was reduced, but the number of fish caught seemed to remain the same.
what is the main, or central, idea of the passage?
to prevent turtles from becoming caught in fishing nets, conservation biologists attached led lights to the nets.
conservation biologists are researching ways to save the threatened sea turtle population.
one problem with small - catch fishing is that sea turtles get caught along with fish.

Explanation:

The passage starts by introducing the problem of sea - turtles getting caught in fishing nets (a side - effect of small - scale net fishing). Then it focuses on the solution: conservation biologists at the University of Exeter attached green LED lights to the nets. The experiment showed that this reduced sea - turtle deaths while keeping fish catches the same. The second option is too general as it just says "researching ways" without specifying the method (LED lights) which is the main focus. The third option only mentions the problem (sea - turtles getting caught) and not the solution (LED lights) which is a key part of the passage's main idea.

Answer:

To prevent turtles from becoming caught in fishing nets, conservation biologists attached LED lights to the nets.