The most effective way to improve performance for read-intensive workloads, such as data analysis from an API, is to offload those queries from the primary database. Dynamics 365 Business Central achieves this using the read scale-out feature, which leverages a read-only replica of the Azure SQL database. Enabling read scale-out in the Business Central admin center is the fundamental step that creates this replica and makes the performance improvement possible. Once enabled, specific objects can be directed to use it.

A. Setting the ODataReadonlyGetEnabled parameter is a global setting for OData GET requests. While it can enforce read-only intent, enabling the underlying read scale-out feature is the primary requirement for performance gain.
B. The AccessByPermission property is a security setting that defines how permissions on related tables are checked. It does not relate to database load balancing or performance optimization.
D. Setting the DataAccessIntent property to ReadOnly on the API page is a necessary step to direct the API's queries to the read-only replica, but it has no effect unless read scale-out (Option C) is enabled first.

1. Microsoft Learn: Using Read Scale-Out for Better Performance. This document states, "To use read scale-out, you have to enable it for the environment from the Business Central admin center." It establishes enabling the feature as the prerequisite for any performance gains.

2. Microsoft Learn: DataAccessIntent Property. The official documentation for this AL property explicitly notes in the first paragraph: "To use this property, read scale-out must be enabled for the environment." This confirms that setting the property is a secondary step that depends on the feature being enabled.

3. Microsoft Learn: Managing Environments in the Admin Center - Read scale-out. This page details the administrative procedure for enabling the feature, describing it as the method to "improve performance by redirecting read-only queries away from the primary database."