Which of the following cannot be appealed?

The correct answer pertains to the amount of the TRICARE-allowable costs. Generally, the allowable charge is established based on TRICARE's reimbursement policies and is not subject to appeal. This is because the TRICARE program has predetermined rates for services and procedures which are established by examining various factors like geographic area and cost patterns. Changes to these rates or negotiations regarding them are more administrative and do not fall under the appeal process.

The other choices involve aspects of coverage or provider choice that can be appealed. For instance, if coverage for a specific condition is denied, individuals have the right to petition for a review of that decision. Similarly, waiting periods tied to enrollment or choices regarding healthcare providers typically involve conditions that may be reconsidered based on individual circumstances or eligibility. This highlights the unique nature of coverage determinations and the flexibility allowed for resolving disputes related to benefits, which contrasts with the fixed nature of the TRICARE-allowable amount.