Concept:Capital expenditure is money spent to acquire, improve, or extend a long-term fixed asset.Explanation:An extension to a building increases the size and value of a fixed asset already in use.Therefore, it is treated as capital expenditure because its benefit lasts for more than one accounting period.Repairs to a generator merely restore it to working condition, so that cost is revenue expenditure.Stock and stationery are purchased for normal trading or office use, so they are also revenue expenditure.Answer:A. extension of building