John has subscribed to a cloud-based service to synchronize data between his smartphone, tablet, and PC. Before allowing the data to be synchronized, this service uses a process in which the cloud service and the client on the smartphone will verify the security of all devices’ security certificates.
What type of security does the cloud-base service employ?
A. Mutual authentication
B. VPN
C. IMAP
D. Tethering

A. Mutual authentication

Explanation:

Mutual Authentication or two way authentication involves two parties in a network connection authenticating each other's digital certificate in order to be assured of the other party's identity.

Since this is as described in the scenario above, the cloud-based service and the devices uses mutual authentication.

answer; availability;

the major difference between the two is the objective and the reward of the game. candy crush has a puzzle theme with the objective of meeting a specific quota of points or objects, you are able to gain access to the next level and compete with peers on the process. on duolingo the objective is rather different, you are given sets of questions for you to answer for you to move to the next level and as for the reward, you are able to learn available language as this is an app developed to teach the user about other languages.