Answer:
From the question, C and D is the answer
Step-by-step explanation:
Business sales grew during the 1800-1900s, due to two following reasons which included advertising public at large which says that a greater brand recognition would familiarize the people with the product as a result increased sales would be witnessed, also allowing customers access to credits so that they would buy more from them .
The growth of business today, is more of thought dependent, but in the earlier times technological advances was not common as compared to now, so radio dependence was mainly used for the advertising of products at large scale, and for customer retention businesses were used to allow certain level of credit to each customer.