There are different APIs for various Check Point products: • Management API — Used to read information, create objects, work on Security Policies and send commands to the Check Point Security Management Server. The Management API has a JSON/XML web services option, a Gaia CLI from the R80.10 SmartConsole, the new mgmt_cli tool, and the Gaia Clish. • Threat Prevention API — A cloud-based service used to control Threat Emulation, Antivirus, and Threat Extraction products. • Identity Awareness Web Services API — A web services API used to add, remove, and show the status of identity parameters. For example, using the API, a new user can be added to an Access Role or a user can be allowed to connect to the internal network from a different IP address. • OPSEC SDK — These APIs are used to open and monitor connections between the Security Management Server and gateways, and other hosts and objects.

As somebody else mentioned, OPSEC SDK isn't strictly listed as an API, but in this SK it's clear APIs do exist. And so I would say D, assuming it's not referring to "Harmony Mobile API". "Starting from R80, OPSEC CPMI commands are considered deprecated and are being replaced by new set of APIs." https://support.checkpoint.com/results/sk/sk63026

Not sure, there is a harmony mobile api, and a identity awareness api, but here are listed mobile access, and identity awareness web services (literally not exactly the same) I dont know the Opsec SDK, but it looks like a toolkit which uses different APIs, So I would say there is no OPSEC SDK API

While OPSEC SDK API is not listed in the repository of available APIs (https://sc1.checkpoint.com/documents/latest/api_reference/index.html,) documentation does exist: https://support.checkpoint.com/results/sk/sk63026.

D is correct, but OPSEC SDK is legacy on R81

D is correct

For me is the OPSEC SDK