Concept:Provision for doubtful debts follows the prudence concept, which is also known as conservatism.Explanation:The prudence concept states that profits should not be anticipated before they are realised.However, all probable losses should be provided for in advance.Doubtful debts represent a possible future loss from credit sales.Making a provision for doubtful debts ensures that the financial statements do not overstate profit or assets.This matches the idea of understating rather than overstating profit when there is uncertainty.Answer:C. prudence concept.