Question: What is the primary purpose of including the direction identifier (DIRECTION) in the computation of message authentication codes?
Option 1: To indicate the type of message being sent
Option 2: To ensure that different input parameter values are used for up-link and down-link messages
Option 3: To specify the encryption algorithm to be used
Option 4: To authenticate the sender's identity
Explanation: The direction identifier (DIRECTION) is included in the computation of message authentication codes to prevent the integrity algorithm from using identical input parameter values for up-link and down-link messages, which could compromise security.