Concept:A higher provision for doubtful debts is an expense, which reduces profit.Explanation:An increase in the provision for doubtful debts is recorded as an additional expense in the income statement.This expense is deducted after calculating the gross profit.Therefore, it reduces the net profit, not the gross profit.So, an increase in the provision for doubtful debts leads to a decrease in the net profit.Answer:C. decrease in the net profit