Remove the vinyl (flooring) and discard it if the ____________ is saturated and/or damaged.

The correct choice is underlayment because it plays a critical role in flooring systems, particularly with vinyl flooring. Underlayment serves as a moisture barrier and provides cushioning and soundproofing. When the underlayment becomes saturated or damaged, it can lead to a range of issues, including mold growth, which can compromise indoor air quality and the structural integrity of the flooring.

If the underlayment is not removed and properly addressed, any residual moisture can continue to affect the flooring above it, leading to further damage. Therefore, when water intrusion is significant enough to saturate or damage the underlayment, it is essential to remove the vinyl flooring and discard the underlayment to effectively mitigate water damage and prevent long-term consequences. This approach ensures that the restoration process addresses the root of the problem rather than just the visible damage.