To instrument a function for context retrieval using the TruLens SDK and clearly differentiate its tracing, the decorator should be used with 'span_type=SpanAttributes.SpanType.RETRlEVAL'. This is directly demonstrated in the source for tracing a function with a specific span type. Option B uses a string literal for 'span_type' , which is not the correct way to reference the enum member. Option C uses 'SpanAttributes.SpanType.GENERATlON' , which is intended for LLM inference, not context retrieval. Option D uses the decorator without a specific 'span_type' , which would not clearly differentiate the context retrieval phase. Option E uses non- existent decorators and types(@trace_function', 'spanTypes').