Question

read the passage.
making towers bird - friendly
the lights on tall communication towers warn pilots to avoid the towers when flying at night. unfortunately, the steady red lights often used on towers have the opposite effect on birds: the bright beams attract and confuse them. instead of avoiding the lights, the birds fly directly toward them, crashing into the towers or becoming entangled in power lines. millions of birds have died this way. however, there is a solution. unlike steady lights, flashing or blinking lights dont attract birds. in response to demands from conservation groups, the federal aviation administration in 2016 began requiring communication towers in the u.s. to use blinking lights instead of steady ones.
what is the main, or central, idea of the passage?
birds are attracted to the steady red lights on communication towers.
to save birds, communication towers have begun using blinking lights.

Explanation:

The passage explains that steady red lights on communication towers attract and confuse birds, causing deaths, and the Federal Aviation Administration started using blinking lights instead to save birds. The main idea is about using blinking lights on towers to protect birds. The first option only states birds are attracted to steady lights (a detail), while the second option captures the main action of changing to blinking lights for bird safety.

Answer:

To save birds, communication towers have begun using blinking lights.