Recently, curators at museums have experienced problems with the preservation of plastic objects, almost all of which disintegrate over time. The Smithsonian collection contains the first-ever plastic toothbrush, which soon will be nothing more than a pile of crumbs. This problem is leading many historians to worry that we will lose the history of our:______
A. Symbolic culture.
B. Signs and gesrutes.
C. Linguistic relativity.
D. Material culture.