Which statement is TRUE about airflow in ABSL$-2$ or ABSL$-3$ rooms?

At ABSL$-2,$ airflow must be directed outwardly from the most contaminated area to the least.

Visual air$-$pressure indicators are not appropriate for ABSL$-3$ rooms.

Exhaust air from an ABSL$-2$ room must pass through a HEPA filter prior to leaving the building.

Discharged air should be directed away from intake vents or personnel areas.

Mark