Question: In a Public Land Mobile Network (PLMN), what modes of establishment are defined for setting up a communication, as described by the attribute associated with a telecommunication service?
Option 1: Only Mobile Originated (MO) and exclusively within the PLMN.
Option 2: Demand Mobile Originated (MO) only, demand Mobile Terminated (MT) only, and demand Mobile Originated or Terminated (MO, MT).
Option 3: Solely Mobile Terminated (MT) for communications originating outside the PLMN.
Option 4: Always a combination of Mobile Originated (MO) and Mobile Terminated (MT) without exclusive options.
Explanation: This is correct because, according to the principles outlined for telecommunication services in a PLMN, the attribute for establishing communication indeed specifies three modes: exclusively demand Mobile Originated (MO), exclusively demand Mobile Terminated (MT), and a flexible demand for either Mobile Originated or Terminated (MO, MT). These options cater to various scenarios of user communication within the PLMN or with external networks.