The best choice for the preservation of non-traditional, temporary art would be 1. photographs.
Photographs provide a way to document the artwork in its original form, preserving its visual and conceptual integrity for future reference. While options like synthetic resin, a glass case, and protective coverings can provide some level of physical preservation, they might not be suitable for temporary art that is intended to be ephemeral or installation-based. In contrast, photographs can capture the essence and context of the artwork without altering or impacting the original piece.