A retail company deploys a machine learning model that classifies incoming customer support tickets into categories like 'Billing', 'Shipping', and 'Technical'. For each ticket, the model returns the predicted category along with a numeric value between 0 and 1 for each possible category. The support team wants to automatically route tickets only when the model is highly certain, and send low-certainty tickets to a human agent. Which characteristic of the model output should the team use to make this routing decision?