Question

eat carrots, see better?
carrots contain high amounts of vitamin a and are good for general eye health. however, carrots will not improve night vision. that myth goes back to british propaganda during world war ii. in 1940, the german luftwaffe, or air force, began bombing britain at night. in response, the british government ordered people to turn off their lights; the government wanted to make it difficult for german pilots to hit their targets. a new technology, radar, allowed the british air force to track and shoot down the german planes without light. to keep the technology secret, the government told the media that their pilots could see the german planes because they consumed so many carrots. consequently, people began to believe that eating carrots would help them see better in the dark.
what is the main, or central, idea of the passage?
during world war ii, the british government told the media that their pilots ate a lot of carrots.
because of a british media campaign, people thought that eating carrots would improve their night vision.

Explanation:

The passage starts by stating carrots are good for general eye health but don't improve night vision. Then it explains the myth of carrots improving night vision originated from British propaganda during World War II. The British government used the story of pilots eating carrots (to hide the radar technology) which led people to believe carrots help with night vision. The second option encompasses this main idea as it connects the British media campaign (the government's story to the media) with people's belief about carrots and night vision. The first option just mentions the government telling the media about pilots eating carrots, not the resulting belief (the main idea of how the myth started and people's belief).

Answer:

Because of a British media campaign, people thought that eating carrots would improve their night vision.