A. Solid
Sound travels fastest through a solid medium. The particles in a solid are closely packed together, allowing sound waves to propagate more efficiently. In liquids, the particles are less densely packed, and in gases, they are even more spread out, resulting in slower sound propagation compared to solids. Plasma is a state of matter where particles are highly ionized, and sound can propagate through it as well, but its properties depend on various factors and can vary widely. However, in general, sound travels fastest in solids.
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~~~Harsha~~~