【单选题】

Before it became one most important symbol for e-mail, the @ symbol (符号) was used to show the cost or weight of something. For example, if you bought 6 apples, you might write it as 6 apples@ $ 1.10 each.

With the introduction of e-mail came the popularity of the @ symbol. The @ symbol or the "at" sign separates a person’s online user name from his mail server address. For instance, joe@ uselessknowledge. com.Although it is widespreadly used on the Internet, there is really no official name for this symbol. Nobody knows how the @ symbol comes on to use
History tells us that the @ symbol was from the tired hands of the monks (和尚).During the MiddleAges before the invention of printing presses, every letter of a word had to be copied by hand for each copy of a published book. The monks looked for ways to shorten the word "at".As a result, the monks circled around the "a" and made the easier symbol.
How did the monks publish a book during the MiddleAges
A、They used a printing press.
B、They use their hands to copy each worD、
C、They used a machine.