To prioritize junior resources without creating rigid "hard constraints" (which might prevent scheduling altogether if no junior is available), you should use Service Objectives (Soft Constraints).

Option C is correct (Resource Priority): By assigning a higher priority value to Junior Service Resource records and adding the "Resource Priority" objective to the scheduling policy, the optimization engine calculates a higher score for these resources. This acts as a general "preference" to use them whenever possible.

Option E is correct (Least Qualified): The "Skill Level" Service Objective has a setting called "Prefer Least Qualified." When enabled, the engine prefers the resource who has the lowest skill level that still meets the job requirement. For example, if a job requires Skill Level 50, and you have a Senior (Level 90) and a Junior (Level 55), the engine will pick the Junior. This is a best practice to prevent "over-qualified" resources (Seniors) from being booked on routine jobs, keeping them free for complex tasks.