Android Debug Bridge (adb) is a command-line tool that lets you communicate with a device. What are its components?

Android Debug Bridge (adb) is a command-line tool that lets you communicate with a device. What are its components?

• A client, a server, and the cloud
• A client, a server, and a daemon
• A server
• A client and a server 

EXPLANATION

Android Debug Bridge (adb) is a versatile command-line tool that lets you communicate with a device. The adb command facilitates a variety of device actions, such as installing and debugging apps, and it provides access to a Unix shell that you can use to run a variety of commands on a device. It is a client-server program that includes three components:

• A client, which sends commands. The client runs on your development machine. You can invoke a client from a command-line terminal by issuing an adb command.
• A daemon (adbd), which runs commands on a device. The daemon runs as a background process on each device.
• A server, which manages communication between the client and the daemon. The server runs as a background process on your development machine.

SOURCE

https://developer.android.com/studio/command-line/adb.html