题目内容：
阅读下列短文，回答题。Maybe ten-year-old Elizabeth put it best when she said to her father, " But, Dad, you can't be healthy if you're dead. "
Dad, in a hurry to get home before dark so he could go for a run, had forgotten to wear his safety belt--a mistake 75% of the US population make every day. The big question is why.
There have been many myths about safety belts ever since their first appearance in cars some forty years ago. The following are three of the most common.
Myth Number One: It's best to be "thrown clear" of a serious accident.
Truth: Sorry, but any accident serious enough to"throw you clear" is also going to be serious enough to give you a very bad landing. And chances are you'll have traveled through a windshield(挡风玻璃) or door to do it. Studies show that chances of dying after a car accident are twenty-five times greater in cases where people are "thrown clear".
Myth Number Two: Safety belts"trap" people in cars that are burning or sinking in water.
Truth: Sorry again, but studies show that people knocked unconscious(昏迷) due to not wearing safety belts have a greater chance of dying in these accidents. People wearing safety belts are usually protected to the point of having a clear head to free themselves from such dangerous situations, not to be trapped in them.
Myth Number Three: Safety belts aren't needed at speeds of less than 30 miles per hour(mph).
Truth: When two cars traveling at 30 mph hit each other, an unbelted driver would meet the windshield with a force equal to diving headfirst into the ground from a height of 10 meters.
Why did Elizabeth say to her father, "But, Dad, you can't be healthy if you're dead?" A．He was driving at great speed.
B．He was running across the street.
C．He didn't have his safety belt on.
D．He didn't take his medicine on time.
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