Final answer:
Norway and Switzerland have a high HDI due to their abundant natural resources, strong education and healthcare systems, and high levels of industrialization, which all contribute to the high quality of life.
Step-by-step explanation:
Countries like Norway and Switzerland have a high Human Development Index (HDI) primarily due to a combination of factors that contribute to a high quality of life for their citizens. One of the key reasons is abundant natural resources, which in the case of Norway includes significant oil and natural gas reserves from the North Sea. Furthermore, both countries have strong education and healthcare systems, which ensure a highly-skilled workforce and maintain high standards of living.
Another contributing factor is the high levels of industrialization, which leads to higher productivity and thus, higher gross domestic product (GDP) per capita. Additionally, unlike options A and D, it's not about the size of the population but rather how the country utilizes its resources and provides services to its population that reflects on its HDI ranking. Hence, a large population size is not a factor in their high HDI.