Question: What is the primary purpose of the EFs (Elementary Files) contained within the USIM Application Dedicated File (ADF) in a Universal Subscriber Identity Module (USIM)?
Option 1: To store subscriber personal data, such as phonebook contacts and SMS messages.
Option 2: To hold service and network-related information for operational purposes.
Option 3: To manage the USIM's cryptographic keys exclusively.
Option 4: To provide a sandbox environment for third-party application testing.
Explanation: The correct answer, Option 2, reflects the primary purpose of EFs in the USIM ADF as stated, which is to contain "service and network related information". This is crucial for the proper functioning of the USIM within a telecom network, enabling it to interact correctly with network services. Options 1, 3, and 4 are incorrect as they do not align with the specified use of EFs in the USIM ADF for service and network-related information.