This question requires more context! To determine which wire is blue, we need additional information. For example:
- What type of wiring are we talking about? Is it electrical wiring in a house, a network cable, or something else entirely?
- What is the purpose of the wiring? Is it used for power, data transmission, or something else?
- What are the other colors of wires present? This can help us identify a standard color code.
Without this information, it's impossible to answer the question.