B, paper will rot in the air for a long time, Mo Bao will not deteriorate, which has nothing to do with the quality of paper, so B is wrong.
C, at room temperature, the chemical properties of carbon are inactive and will not react with other substances in the air, so C is correct.
D, although modern science and technology can restore calligraphy, it has changed the original essence, so D is wrong.
So choose C.