阅读下面短文，从短文后各题所给四个选项（A、B、C和D）中，选出可以填入空白处的最佳选项，并在答题卡上将该项涂黑。
Mother's Day is an important holiday all over the world. The idea for Mother's Day 1 an American woman named Anna Jarvis. Anna hoped there would be a day for people to show 2 to their mothers, so she wrote many letters to important people of her time. In 1914, the second Sunday in May was celebrated as Mother's Day. People in Denmark, Ital, Turkey, Australia and Belgium all celebrate Mother's Day on the same day as Americans. The day gives people a good 3 to thank mothers. People of all ages do many things to make the day special for their mothers. A typical way is to make Moms stay 4 in bed. That means a mother doesn't need to 5 early to make breakfast for her family. 6, the rest of the family make breakfast for her. Kids do secret things to 7 their moms. They write love letters to their moms. Some even make gifts themselves for their moms. Anna Jarvis's mother 8 carnations, so people chose carnations as a present for their mother on Mother's Day. Carnations of different 9 have different meanings. People buy red carnations if their mothers are 10. However, white ones are used to express love to dead mothers.
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，∠ABC=45°，求OH的长．