Public key encryption utilizes a pair of encryption keys obtained through .

Public-key encryption is an  encryption scheme that uses two keys: a public key and a private key. The public key is known to everyone while the private key is known only to the recipient.Public key encryption utilizes a pair of encryption keys obtained through a Certificate Authority.  Certificate Authorities are entities that issue Digital certificates, which are used for  secure transport and sharing of public keys.

i think the answer is b.

it most likely is charging, however when using a hot spot, it drains straight through battery life.