Please answer the following question: Read the article and select the best answer. Article: The first chocolate was eaten by people in Central and South America hundreds of years ago. In those days, people did not really eat chocolate; the cocoa bean was used to make a chocolate drink that the people enjoyed very much. Much later the cocoa bean was brought to Europe and people there also came to love the taste of it. In 1824, John Cadbury opened a small shop in Birmingham. One of the items he sold was cocoa powder to be made into drinks. In 1831, he opened a small factory to make cocoa powder from cocoa beans. John Cadbury believed that alcohol was an important cause of people's being poor, and he wanted to encourage people to drink chocolate instead. A few years later a man called Joseph Fry invented a way to make chocolate bars, and so for the first time people had the chance to eat chocolate instead of only drinking it. At first, chocolate was luxury and only the rich people could buy it. Later, as more and more chocolate bars were produced and sold, they became cheaper. However, at first, only plain chocolate was produced. Milk chocolate came later and this was made by adding milk or milk powder to the chocolate. Cadbury introduced their first milk chocolate bars in 1897. Their most famous chocolate, Cadbury's Milk Bar, was introduced in 1905. It has been a best-seller in Britain and around the world for nearly 100 years. The Cadbury factory is still in Birmingham and the chocolate produced there is eaten all over the world. Every year, thousands of visitors visit the factory to see how chocolate is made. Question: People started to eat chocolate when _ . Options: A: milk was added to chocolate B: more milk chocolate was made C: chocolate became cheaper D: chocolate bars were made
A:
D