Final answer:
The effect of a handle on the pressure of thin liquids at higher pressures cannot be determined without additional context, but in a hydraulic system, manipulating a handle usually leads to changes in pressure. Therefore, correct option is 4.
Step-by-step explanation:
What the handle does with thin liquids at relatively higher pressures depends on the context provided in the question. However, considering the principles of physics, specifically the concept of Pascal's law, the handle might be part of a mechanism in a hydraulic system.
In this system, applying force to a piston handle will increase the pressure of the liquid within the confines of the system. If the liquid is incompressible and the system is sealed, the pressure can be assumed to be distributed evenly throughout the liquid, affecting the entire system's pressure.
When you increase the pressure in one part of the hydraulic system (by pushing the handle), the pressure throughout the liquid increases accordingly. On the other hand, releasing the handle or allowing the liquid to move to a larger area could decrease the pressure.
Without more detail, such as whether this is a closed system, the presence of valves, or the intent of the handle movement, it is not possible to determine precisely if the handle increases, decreases, or maintains the pressure.