Which one of the following is not a sub-index of the World Bank's Ease of Doing Business Index?

1. The World Bank's Ease of Doing Business Index ranked countries based on regulations directly affecting businesses. 2. The index comprised several sub-indices or indicators measuring specific aspects of business regulation. 3. Key indicators used (around 2019) included Starting a Business, Dealing with Construction Permits, Getting Electricity, Registering Property, Getting Credit, Protecting Minority Investors, Paying Taxes, Trading Across Borders, Enforcing Contracts, and Resolving Insolvency. 4. Options (B) Paying taxes, (C) Registering property, and (D) Dealing with construction permits were all established indicators within the Ease of Doing Business Index. 5. Option (A) Maintenance of law and order, while crucial for a stable business environment, was not measured as a specific, separate sub-index within the methodology of the World Bank's Ease of Doing Business Index. The index focused more narrowly on specific regulatory processes. 6. Therefore, 'Maintenance of law and order' is not a sub-index of the Ease of Doing Business Index.