阅读下面的短文，并根据短文内容回答问题(本题共18分，每小题2分)

How Can a Small Stamp Be Worth $16,800?

Any mistake made in the printing of a stamp raises its value(价值)to stamp collectors. A mistake on a two-penny(便士，英国辅币) stamp has made it worth a million and a half times its face value.

Do you think it impossible? Well, it is true. And this is how it happened.

The mistake was made more than a hundred years ago in the former British colony(前英殖民地) of Mauritius, a small island in the Indian Ocean. In 1847 an order(订货单) for stamps was sent to London. Mauritius was about to become the fourth country in the world to put out stamps.

Before the order was filled and the stamps arrived from England, a big dance was planned by the commander-in-chief of all the armed forces on the island. The dance would be held in his house and letters of invitation would be sent to all the important people in Mauritius. Stamps were badly needed to post the letters. Therefore, an islander, who was a good printer, was told to copy the pattern of the stamps. He carelessly put the words “Post Office” instead of “post Paid”, two words seen on stamps at that time, on the several hundred that he printed.o post the letters. There

Today, there are only twenty-six of these misprinted stamps left-fourteen One-penny Reds and twelve Two-penny Blues. Because there are so few Two-penny Blues and because of their age, collectors have paid as much as $ 16,800 for one of them.

在A、B、C、D 四个答案中，选出正确的一个，把它前面的字母填在左边的括号内。原文不得作任何改动。

Why did Mauritius print some stamps too? Because __