Question: What happens when a USIM application session is already active and a command with CLA (Class Byte) set to 'A0' is sent to the UICC?
Option 1: The UICC initiates a new GSM session in parallel.
Option 2: The command is processed normally, ignoring the active USIM session.
Option 3: The UICC returns SW1SW2 '6E 00' (class not supported) to the terminal.
Option 4: The active USIM session is automatically terminated to process the new command.
Explanation: According to specified interaction and restrictions between GSM/USIM applications, when a USIM session is active, commands with a different class (CLA 'A0' for GSM) are not supported. Thus, the UICC responds with a 'class not supported' error (SW1SW2 '6E 00') to maintain session type exclusivity.