Final answer:
To configure the designation requirements for the Employee plus One option in both Medical and Insurance plans, you would select option C and choose the appropriate designations for each plan type.
Step-by-step explanation:
To configure this requirement, you would choose option C. This option allows for both spouse and domestic partner as allowed designations. For the Insurance Plan type, you would only select spouse as the allowed designation. And for the Medical Plan type, you would select both spouse and domestic partner as the allowed designations.