A、In the 18th century. B、In the 19th century. C、In the 20th century. D、Before the industrial revolution. B短文中提到，在19世纪糖果业开始发展的时候，

Can you imagine being able to buy something with just a penny? Throughout much of American history, children looked forward to the treat of penny candy when they went to the store. Penny candy emerged in the 1800s for the first time. Prior to the industrial revolution, candy was expensive to make.(11)As the candy industry developed in the 19th century, manufacturers were able to produce large quantities of very inexpensive candies. Many stores across the United States carried penny candy, and children shopping with their parents always looked forward to the sweet treat.(12)In the 19th century, penny candy was not wrapped in anything—store owners placed the candy in large glass jars that had either glass,or metal lids. Most early candies were hard candies. By the late 1800s and early 1900s, many other types of candies were making appearances in these jars. By the latter part of the 20th century, it became more and more difficult to find penny candy. In part, the types of stores that had carried penny candy,(13)commonly known as general stores because they carried so many different items, were disappearing.(14)Grocery stores took their places, and these stores did not have employees available to count out individual pieces of candy.
11. When did the candy industry begin to grow?
12. Where did store owners put penny candies in the 19th century?
13. What can be inferred about general stores?
14. Why is it difficult to find penny candies in grocery stores?