Accounting policies refer to the specific principles, rules, and procedures adopted by an organization in preparing and presenting its financial statements. These policies guide the organization in selecting and applying accounting treatments for various transactions and events.

There are four options provided, and the correct answer is option 'D' - changing from concern to concern. Let's understand why this is the correct answer:

Prescribed by AS 1:
- AS 1 (Accounting Standards 1) is a standard issued by the Institute of Chartered Accountants of India (ICAI) that deals with the disclosure of significant accounting policies.
- While AS 1 provides guidelines and recommendations for selecting and applying accounting policies, it does not prescribe specific policies.
- Different organizations may have different accounting policies based on their specific circumstances, nature of business, industry practices, etc.

Laid down by Law:
- Accounting policies are not prescribed by law in most countries, including India.
- While there may be legal requirements for certain disclosures in financial statements, the specific accounting policies are usually determined by the organization and its management.

Same for all concerns:
- Accounting policies are not the same for all concerns.
- Different organizations may have different policies based on their specific circumstances, industry practices, and management's judgment.
- For example, one organization may choose to use the straight-line method for depreciating its fixed assets, while another organization may choose to use the diminishing balance method.

Changing from concern to concern:
- The correct answer is option 'D' because accounting policies can vary from concern to concern.
- Each organization has the flexibility to select accounting policies that are most appropriate for its operations, financial reporting objectives, and compliance with applicable accounting standards.
- Factors such as nature of business, industry practices, regulatory requirements, and management's judgment influence the selection and change of accounting policies.

In conclusion, accounting policies are not prescribed by AS 1 or laid down by law. They are not the same for all concerns and can vary from concern to concern based on various factors. The correct answer is option 'D' - changing from concern to concern.