Concept:
Document analysis is an important qualitative research method in social research.
Step 1:
Researchers study written documents, reports, records, and texts to identify patterns and meanings.
Step 2:
Thematic analysis identifies recurring themes, ideas, and patterns within documents or qualitative data.
Step 3:
It helps researchers interpret meanings and understand social issues systematically.
Step 4:
• Performatory analysis is not a standard document analysis method.
• Informal content analysis is not the recognized term here.
• Oral communication is a communication process, not document analysis.
Step 5:
Hence, the correct answer is Thematic analysis.
\[
\boxed{\text{(3) Thematic analysis}}
\]