What is significant about the left side of the Lincoln MRV?

The left side of the Lincoln MRV being cut irregularly is significant because it serves as a security feature to deter counterfeiting and ensure the authenticity of the document. Irregular cuts can complicate replication efforts because they are not standard and can easily be identified. This characteristic is part of a broader set of security measures that help differentiate genuine documents from forgeries.

While the other options mention features that may pertain to various aspects of security or design, the irregular cut specifically aids in preventing unauthorized reproductions, making it a distinctive and practical aspect of the document's security design.