Final answer:
The question pertains to the use of dampers for precise flow control in engineering systems. It is likely focused on damper configurations or types, which are integral in systems requiring precise airflow or fluid control.
The context needed to choose a specific damper type is missing, as the mention of vessels and pistons seems to be unrelated to the list of damper options.
The Correct Option is: C. Opposed
Step-by-step explanation:
The question appears to be addressing the topic of flow control within engineering systems, specifically focusing on components known as dampers. Dampers are devices used to regulate the flow of air, gas, or liquid by modulating the size of the flow passage.
The options provided (Variable drain inlet, Parallel, Opposed, Pilot position, and Horizontal) likely refer to different types of dampers or configurations that can affect hydraulics or airflow in systems such as HVAC, combustion engines, or fluid transport mechanisms.
To pinpoint which type of damper is used for precise flow control, it's important to understand how each operates. While 'Parallel' and 'Opposed' could refer to the orientation of the damper blades,
'Pilot position' might imply a control system that is used to finely adjust the damper's setting, which suggests it might be the most accurate choice for precise control. Without context such as Figure 3.12 or descriptions of Vessel A and Vessel B, a definitive answer cannot be provided.