Question: What happens when the getItemIdentifier() method is invoked but the item identifier TLV element is not present in the (U)SIM's toolkit applet?
Option 1: The method returns a default byte value.
Option 2: The method throws ToolkitException.UNAVAILABLE_ELEMENT.
Option 3: The method returns an empty array of bytes.
Option 4: The method hangs until the TLV element becomes available.
Explanation: According to conformance requirements, if the item identifier TLV is not present, the getItemIdentifier() method must throw a ToolkitException with the reason code UNAVAILABLE_ELEMENT, ensuring predictable handling of absent expected data within the (U)SIM's toolkit environment.