Final answer:
When both BLOWER and EXTRACT buttons are in OVRD mode in a ventilation system, it usually means the system will operate at maximum capacity, overriding normal controls.
Therefore, the answer to the question would be D)
Step-by-step explanation:
In a ventilation system, when both BLOWER and EXTRACT pushbuttons are in OVRD (override) mode, it typically suggests that the system has been manually set to operate in a specific, non-standard way.
The exact effect of this setting can vary depending on the specific ventilation system's design.
However, for many systems, the override mode allows the system to operate at maximum capacity, overriding any automatic controls or presets that would normally regulate airflow based on system sensors or timers.
Therefore, the answer to the question would be D)