Which of the following, if true, would most directly explain the higher long-distance charges incurred by residential users? A. More long-distance calls are made by businesses than by residential users. B. Telephone companies are expanding their services in the areas of computing and data processing. C. Rates for calls made during the evening, the time when most residential users make long-distance calls, have increased. D. Increased competition has led telephone companies to expand their budgets for the development of new technology. E. Telephone companies must receive approval from regulatory agencies before putting rate changes into effect.