1. The problem asks to identify the accounting concept that governs the recognition of sales revenue when goods and services have been supplied and costs when goods and services have been received. 2. The key point is that revenue and costs are recognized when they are earned or incurred, not necessarily when cash is received or paid. 3. This principle is known as the Accruals concept, which states that transactions should be recorded in the periods to which they relate. 4. The other options are: - Materiality concept: focuses on the significance of information. - Realization concept: revenue is recognized when it is earned and realizable. - Dual aspect concept: every transaction affects two accounts. 5. Since the question emphasizes recognizing revenue and costs when goods/services are supplied/received, the correct answer is the Accruals concept. Final answer: 1. Accruals concept