Question: What is the primary trigger for detecting a Transfer Syntax Error in UTRAN Iur interface RNSAP signalling?
Option 1: Receipt of an unknown protocol message
Option 2: Failure to establish a logical connection
Option 3: Expiration of a timer during a procedure
Option 4: Failure in ASN.1 decoding process due to syntax violations
Explanation: A Transfer Syntax Error is fundamentally related to the inability to decode received messages correctly, which directly points to issues with the Abstract Syntax Notation One (ASN.1) decoding process, crucial for interpreting message syntactical structure in telecom protocols.