How does a wireless network key work with an encrypted wireless network?

Question $107$ options:

$1)$

The wireless key is the encryption code needed by the receiver to decode the file.

$2)$

The sending and receiving devices must know the wireless network key to communicate.

$3)$

The wireless network needs the key to decode the data before sending.

$4)$

The wireless network key is your password for logging onto an Internet email system to receive files.