MPO polarity A/B/C defines what aspect?

• A. Determines color coding of the connector.
• B. Controls the physical orientation of the MPO housing.
• C. Defines fiber lane mapping; wrong polarity prevents TX-RX pairing.
• D. Specifies the number of fibers in the trunk.

Answer: (C)

MPO polarity defines how the individual fiber lanes inside the connector are mapped from one end to the other, so transmit (TX) lanes align with receive (RX) lanes on the opposite side. This lane-to-lane mapping is what makes a link work across MPO connections.

Why this is the best answer: If the polarity is set correctly, the TX fibers on one end map to RX fibers on the other end, allowing the light signal to be received properly. If the polarity is wrong, TX fibers connect to TX fibers (or to non-receiving paths), so the RX side never gets the signal and the link fails despite the physical connection being present.

Color coding, physical orientation of the MPO housing, or the total number of fibers are separate considerations and do not define polarity. Polarity is specifically about ensuring the lanes are mapped correctly to permit TX-RX pairing across the link.