In SAP S/4HANA Cloud Public Edition, side-by-side extensibility leverages the SAP Business Technology Platform (BTP) to host custom extensions. Here’s why this is the correct answer:

Side-by-side extensibility (B):This approach involves developing and deploying custom applications on the SAP BTP, which runs independently of the core S/4HANA system. It allows for greater flexibility and scalability while ensuring minimal impact on the core system.

Classic extensibility (A):Classic extensibility refers to modifications made directly within the SAP system, which is not supported in the public cloud edition due to its standardized nature.

Key user extensibility (C):Key user extensibility allows for in-app customizations, such as adding fields or logic, but it does not involve hosting extensions on SAP BTP.

Developer extensibility (D):Developer extensibility typically refers to custom developments within the system, which is limited in the public cloud edition.