In preparing for a future inspection, which of the following assessments can be used to...

Per Section 13.3 of API 580:

“A Fitness-For-Service (FFS) assessment (e.g., API 579-1/ASME FFS-1) may be performed to determine what size flaws, if found in future inspections, would require repair or equipment replacement.”

This makes Fitness-For-Service the correct method for evaluating whether existing or predicted flaws are tolerable or require corrective action.