Final answer:
The first line in a SALT transcript begins with a symbolic identifier, which is used to identify the speakers in the transcript.
Step-by-step explanation:
The first line in a SALT (Systematic Analysis of Language Transcripts) transcript begins with a symbolic identifier and is used to identify the speakers. This means the correct option here is Option 4: Symbolic identifier. The symbolic identifier usually consists of a set of initials or a single letter that represents the speaker throughout the transcript.