The correct use case for using the specified certificate file format is option B, using a PKCS12 file to install a certificate along with its private key on a device. PKCS12 is a binary format for storing a certificate chain and private key in a single encrypted file. PEM files are Base64 encoded certificate files and are typically used for storing certificates, not private keys, and PKCS7 is used for certificate chains without the private key.
These answers are based on general networking and security practices, specifically within the context of Aruba network device configurations. If you have questions specific to Oracle Database 12c SQL, please provide the relevant details or ask separate questions related to that topic.