Concept:An item mistakenly treated as an expense should be added back to revenue in the adjusted profit and loss account.Explanation:Revenue of #15,000 was wrongly recorded as expenses.Therefore, it was omitted from revenue and must be added back as an adjustment.The expenses of #4,000 wrongly recorded as revenue should be deducted from revenue, not added.So the amount to be added to revenue is #15,000 only.Answer:C. #15,000