* A. Use fewer drill-down characteristics in the initial view: This can improve the query performance by reducing the amount of data that needs to be transferred and displayed at the start of the query execution. The user can drill down to more details later if needed1.
* D. Use mandatory characteristic value variables: This can improve the query performance by restricting the data selection to a smaller set of values that are relevant for the user. The user can also change the variable values later if needed1.
* E. Use include functions in the restricted key figures: This can improve the query performance by avoiding unnecessary calculations and aggregations that are done when using exclude functions.
Include functions are also more efficient than selections or restricted key figures when filtering data1.
Reference:
* 2 https://blogs.sap.com/2015/04/20/query-performance-optimisation-tips-in-bw-73/
* 1 https://blogs.sap.com/2022/02/02/query-performance-optimization-in-bw-few-tips/
* 3 https://help.sap.com/doc/00f68c2e08b941f081002fd3691d86a7/2022.12/en- us/0471d0ecea4e4677ba29d9ac1496c24c.html
* 4 https://blogs.sap.com/2021/06/02/sap-bw-4hana-performance-optimization-part-i/

* C. SAP ABAP Connection: This is what you need to use to combine data from a non-sap system and an InfoCube of your SAP BW powered by SAP HANA system using SAP Data Warehouse Cloud. You can use an SAP ABAP connection to connect to your SAP BW system and access the InfoCube data as a remote table. You can then join this remote table with the data from the non-sap system that you have already loaded into SAP Data Warehouse Cloud using a graphical view12.
Reference: * 1 https://help.sap.com/doc/00f68c2e08b941f081002fd3691d86a7/release/en- US/0c9d6f0a6c4a4b8e8b3f7e5c0a3d6f9d.html
* 2 https://help.sap.com/doc/00f68c2e08b941f081002fd3691d86a7/release/en- US/5c9a6c8b6c4a4b8e8b3f7e5c0a3d6f9d.html