Pascal's Law applies only to __________.

Pascal's Law is focused on the behavior of fluids at rest, specifically stating that when pressure is applied to a confined fluid, the pressure change occurs equally throughout the fluid in all directions. This fundamental principle is essential in understanding how hydraulic systems operate, where the force applied in one area can be transmitted through the fluid to produce a proportional force in another area of the system.

When the question specifies "confined fluids," it aligns perfectly with the definition and application of Pascal's Law, emphasizing that the law is about the behavior of fluids when they are held in a closed system. This confinement ensures that the pressure is uniformly distributed, leading to predictable outcomes when force is applied.

Other options mention specific types of fluids or conditions, such as high octane fluids, gases, or fluids in motion, but they do not encapsulate the core principle of Pascal's Law, which is specifically applicable to fluids that are contained. This makes the focus on confined fluids the correct answer in the context of the question.