After completing a load forecast, generating units should be assigned for which of the following?

The assignment of generating units after completing a load forecast primarily revolves around ensuring that there is enough capacity available to meet both current and future demand, which includes fulfilling reserve obligations. Reserve obligations are critical because they ensure that there is backup power available in case of unexpected outages or increases in demand. This is a key aspect of maintaining system reliability and stability in the electric power sector.

While the other elements mentioned, such as energy transfers, losses, and entity requests, may play important roles in overall system operations, the most immediate need after a load forecast is to focus on ensuring that reserve obligations are met. Assigning generating units to cover these obligations is a fundamental part of effective load management and operational planning in power systems.

Therefore, focusing solely on reserve obligations directly addresses the immediate concerns of reliability following a load forecast, making it the correct answer.