According to Oracle documentation3, when using FBDI template to load Chart of Account Mapping Rules for their Primary and Secondary ledgers, you can create, update, and delete account rules for a chart of accounts mapping, and you can create, update, and delete segment rules for a chart of accounts mapping. FBDI enables you to import chart of accounts mapping rules from a spreadsheet template into General Ledger. You can use FBDI to manage both account rules and segment rules for a chart of accounts mapping. Therefore, options C and D are correct. Option A is incorrect because you can download the template from other pages besides the Manage Chart of Accounts Mappings page. Option B is incorrect because FBDI does not support external integration using REST services.

Data access sets are collections of ledgers that define the data security for users who access General Ledger.
Users can only access the ledgers that are assigned to them through data access sets. To allow users with the General Accountant job role to access the UK Ledger, you need to create a data access set that includes the UK Ledger and assign it to the user/role combination. You also need to specify the access privilege for the data access set, which can be Full Ledger, Both Read and Write, or Read Only. In this case, you need to select Both Read and Write to allow read/write access to the full ledger. References:
* Implement General Ledger
* GL_ACCESS_SET_LEDGERS
* The Default Data Access Set
* Overview of General Ledger Security