The correct answer is D. Time.
Intertemporal allocation of resources is the process of allocating resources across different time periods. This means that decisions are made about how to use resources today in order to meet future needs. For example, a company might decide to invest in research and development today in order to create new products in the future.
The other options are incorrect because they do not refer to different time periods. Option A, needs, refers to the different things that people or organizations need. Option B, sectors, refers to different areas of the economy, such as agriculture, manufacturing, and services. Option C, space, refers to different geographic areas.
Intertemporal allocation of resources is an important concept in economics because it helps to ensure that resources are used efficiently. By making decisions about how to use resources today in order to meet future needs, businesses and governments can avoid wasting resources and can ensure that they are available when they are needed.