根据短文理解，从A、B、C、D四个选项中选择正确答案填空。
Latchkey Kids
Are you home only yourself after school? No one knows how many 1 are home after school and no parents at home, but they know the 2 is in the millions(百万). Kids who take care of themselves are sometimes 3“latchkey” kids.
This nickname got its start in the 1940s, 4 World War II. The men were away at war, so man y women had to take jobs in factories to 5 the country going. With both parents away, lots of kids went back to a 6 man's home after school. Latchkey kids wore a house key around their 7 and this key opened the front door or latch.
Today, it's common for 8 parents to work or for kids to live with just one parent, so a new group of kids is spending 9 no one with them after school. Many schools now have after-school activities, 10 some don't, and in some cases, families may not be able to pay for the more money.