More is the refractive index of a medium, lesser is the speed of light in that medium. Thus, speed of light is highest in water than in oil as oil is denser than water.
I would say the water is quicker Sound travels fastest through more dense materials. Oil is more is less dense than water, meaning that sound travels faster through water than oil.
Hope it helps and have a good day..!!!!!
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Apoorv answered this
sound travel faster in oil because it is more denser and thicker than water. hope this helps...........