The correct answer is: [D]: " milk " .
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Choice [A]: "soil" is incorrect; since "soil" is "heterogeneous" {composed of many different "ingredients" .].
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Same with "Choice [B]: "granola" [composed of many different ingredients—clumps of sweetened oats, raisins, coconuts, etc.].
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Same with "Choice [C]: "salad dressing". {Notice how we usually have to "shake the bottle" ? Composed of multiple ingredients, (e.g. oil, vinegar, and spices, or oil and other spices, and more ingredientes).
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Choice: [D]: "milk", as a liquid, is a single, well-mixed, uniform, mixture; as such, it is "homogeneous". Note: "homo-" means "same".
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