阅读下列短文，从每题所给的四个选项(A、B、C和D)中选出最佳选项。
Old Wives' Tales are those "helpful" things that your grandparents say that are probably not true. They are things like, "If you eat carrots, you'll see well in the dark", or "If you eat cheese at night, you'll have bad dreams". But are they nonsense (胡说) or is there sometimes a little bit of truth in them? We decided to find out more.
Let's start with a famous one: "An apple a day keeps the doctor away". Well, of course everyone knows that fruit is important for health. But can one apple really make a difference? A medical study from 2013 says "yes". It found that if people over 50 eat an apple a day, their chances of heart problems are much smaller than people who don't.
What about "Gain a child, lose a tooth"? They say that when a woman has a child, a tooth will fall out. Researchers studied more than 2,600 women between the ages of 18 and 64 with one or more children and guess what? They found they had more problems with their teeth than women with no children, although they couldn't say exactly why.
My great uncle was a big believer that "fish is brain food". It looks like he might be right. Fish have a lot of omega-3 and omega-6 fats in their oil. Some scientists studied 120 primary school children, and they discovered that the children who ate omega-3 and omega-6 made big improvements in their schoolwork. If you eat fish oil, it will help to prevent heart problems, too. It seems like eating fish is a good idea.
Finally, what about those carrots? Can they really help your night vision? I've eaten them all my life, but I still walk into things when I get up in the night. Unluckily, I can't find anything to show if this is right or wrong. I'll keep looking and I'll let you know as soon as I find out.
