Final answer:
A consumption matrix and production vector can be applicable in this context when the final external demand is given.
Step-by-step explanation:
A consumption matrix is a tool used in economics to represent how different sectors of an economy consume goods and services. It shows the quantity of each good or service consumed by each sector. A production vector, on the other hand, represents the output or production levels of each sector. To satisfy a final external demand of 18, we need to find a production vector that can meet this demand while considering the consumption matrix.
However, based on the given options, it seems that the question is asking whether the consumption matrix and production vector are applicable in this particular context. Option (D) states that both the consumption matrix and production vector are applicable, with the final external demand given as 18. Therefore, the correct answer is option (D).