Final answer:
Infectious diseases are more prevalent in developing countries primarily because of the lack of health services and the inability of individuals to afford care, making options 'A' and 'D' correct(e).
Step-by-step explanation:
Infectious diseases are a much greater problem in developing countries than in developed nations due to a variety of factors. One main reason is that developing countries generally lack many of the health and medical services found in developed countries, which are essential in combating infectious diseases. Public sanitation efforts, access to clean drinking water, and availability of medical care, including antibiotics, are not always available or are of lower quality in developing nations. Furthermore, even when medical care is available, another significant barrier is economics as many people in developing nations do not have the money to pay for it, which can include the costs associated with medications and healthcare services. Hence, the most accurate answer here would be 'E) Both A and D.'