C=C, the double carbon bond creates a kink in the chain of carbons, and prevents the fats from stacking neatly and forming a solid. The double carbon bonds present in canola oil are why it is a liquid at room temperature, while the lack of such bonds in butter allows for the molecules to lay flat on one another, making butter a solid.
Hello there, fellow human being!
The answer is D. unicellular.
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~Ruru