Which is the topic sentence of the following paragraph? ( ) A. There are lots of people who try to get benefits by dishonest means. B. For example, many students copy the papers written by others or cheat at examinations in order to get higher marks. C. The same thing may be true to some manufacturers who try to get rich by making fake and poor products. D. Those people may succeed for a time, but sooner or later, they will acquire nothing but a bad reputation.