Answer:
S/MIME
TLS
SFTP
Explanation:
S/MIME (Secure/Multipurpose Internet Mail Extensions) is a protocol that is generally accepted for sending encrypted messages or sign them after encrypting.
TLS is also considered a cryptographic protocol that is known for providing safe and secure communication security over networks and are in most cases used for internet communications.
SFTP also known as SSH or Secure File Transfer Protocol is a network protocol that allows for the transfer, access, and management of files over reliable and secure data stream.
Hence, a company executing a strategy to encrypt and sign all proprietary data transit can use these 3 protocols.