The Greatest Drawback to Archival Analysis Is That

The greatest drawback to archival analysis is that

A) archival data are very difficult to obtain.
B) what gets recorded in the archives of a society changes over time.
C) it is very difficult to train researchers to code archival data accurately.
D) archival data are invariably biased by the researcher's preconceptions.
E) archival data were not originally recorded to test hypotheses,so they may be incomplete.