Which workplace scenario does not meet the criteria for a sufficient fall protection plan?

Using warning signs alone on elevated surfaces does not meet the criteria for a sufficient fall protection plan because it does not provide an active means of preventing falls. While warning signs can serve as a way to alert workers to potential hazards, they do not physically protect individuals from falling. A robust fall protection plan typically includes physical barriers like guardrails or safety nets, which actively prevent falls from heights. Additionally, training is an essential element that helps employees recognize and understand fall hazards, but it must be complemented by physical safety measures to be effective. Therefore, relying solely on signage is inadequate to ensure worker safety in elevated work situations.