The central problem of "What to produce?" in economics involves deciding which goods and services should be produced given the limited resources. This problem is mainly concerned with the following considerations:
1) What type of goods to produce? This involves deciding the specific kinds of goods and services that should be produced to meet the needs and preferences of consumers.
2) What quantity of goods to produce? This involves determining the amount of each good or service to produce in order to satisfy consumer demand and achieve optimal resource allocation.
Therefore, the correct answer is: (B) and (D) only as they directly pertain to the types of goods and the quantities required in the production decision.