Question: What does a `TP-Validity-Period-Format (TP-VPF)` value of `01` (bit4=0, bit3=1) indicate in an SMS-SUBMIT message's first octet?
Option 1: TP-VP field is present with an enhanced format
Option 2: TP-VP field is not present
Option 3: TP-VP field is present with a relative format
Option 4: TP-VP field is present with an absolute format
Explanation: According to the defined values for TP-Validity-Period-Format (TP-VPF), a setting of `01` indicates that the TP-VP field is present and utilizes an enhanced format, crucial for determining how the SMS message's validity period is interpreted by the Short Message Service Center (SC).