Final answer:
The U.S. Department of State has created a rating system on difficulty associated with various regional assignments.
Step-by-step explanation:
The correct answer is c. U.S. Department of State.
The U.S. Department of State has created a rating system on difficulty associated with various regional assignments. This rating system helps assess the level of difficulty and risk involved in different assignments and allows the department to allocate resources appropriately. For example, an assignment in a politically unstable region may be rated as high difficulty and may require additional security measures. The U.S. Department of State plays a crucial role in managing and overseeing U.S. foreign policy and international relations.