The correct answer to this question is option 'B' - Money measurement concept. Let's understand why this concept prevents the accountants from taking the management's incompetence into account while preparing the book of accounts.

The money measurement concept is a fundamental accounting principle that states that only transactions and events that can be expressed in monetary terms should be recorded in the accounting records. In other words, only the financial aspects of a transaction are considered, not the qualitative aspects.

Explanation:
1. Limitation of Monetary Terms: The money measurement concept is based on the assumption that only transactions that can be measured in monetary terms are relevant to the accounting process. As a result, any qualitative aspects of the management's incompetence, such as their decision-making abilities or leadership skills, cannot be quantified or expressed in monetary terms. Therefore, the accountants cannot take this into account while preparing the books of accounts.

2. Objective and Reliable Information: The primary objective of accounting is to provide reliable financial information to the users of financial statements. By focusing only on monetary aspects, the accountants ensure that the financial information is objective, verifiable, and consistent. Including subjective assessments of management's incompetence would undermine the reliability and objectivity of the financial statements.

3. Consistency and Comparability: The money measurement concept ensures consistency and comparability in financial reporting. If accountants were allowed to consider management's incompetence, it would introduce subjectivity and inconsistency in the preparation of financial statements. This would make it difficult for stakeholders to compare the financial performance and position of different firms.

4. Legal and Regulatory Requirements: Accounting standards and regulations, such as Generally Accepted Accounting Principles (GAAP) or International Financial Reporting Standards (IFRS), require financial statements to be prepared in accordance with the money measurement concept. Accountants are bound by these standards and must adhere to them while preparing the books of accounts.

In conclusion, the money measurement concept prohibits accountants from considering management's incompetence while preparing the book of accounts because it focuses solely on transactions and events that can be expressed in monetary terms. This ensures the objectivity, reliability, consistency, and comparability of financial information.