The correct answer is C. Schedule compliance. A leading indicator measures whether the behaviors and processes that create future performance are being executed correctly. Schedule compliance shows whether planned maintenance work is actually being completed as scheduled. If schedule compliance is poor, the organization is likely to experience more deferred work, reactive maintenance, schedule breaks, backlog instability, and lower future reliability. Achieved availability is not a leading indicator; it is normally a lagging result showing what equipment availability was achieved after the operating period. Plant profitability is even more lagging and broader because it is affected by production volume, market pricing, reliability, labor cost, energy cost, quality, and many other business factors. In CRL Work Execution Management, schedule compliance matters because planning and scheduling only create value when the committed work is executed. Maintenance KPI guidance identifies planned maintenance and compliance-style measures as leading indicators because they predict future reliability and maintenance outcomes.