Biological tests (personnel, product, and cross-contamination protection) should be performed onBSCs to determinea. when the cabinet has been moved to a new location for a different use.b. when it is necessary to determine whether the cabinet has been improperly used.c. annually, but can be done using tracer gas instead of bacteria.d. only after the unit has been broken in for two weeks.e. if aerosols are contained, outside contaminants do not enter the work area, and contamination within the cabinet isminimized.