Final answer:
The correct statement is that double bonds can be found in an unsaturated fatty acid. They are shorter than single bonds and restrict rotation, creating a planar structure.
Step-by-step explanation:
Among the statements provided about two carbon atoms double-bonded to each other (C=C), the correct one is that double bonds can be found in an unsaturated fatty acid. Double bonds have a significant impact on the molecular structure and properties of fatty acids.
Unlike single bonds, a carbon-carbon double bond is shorter and does not allow for free rotation, because it has both a sigma (o) and a pi (\u03c0) bond, which creates a rigid planar structure. This rigidity is responsible for the different properties of unsaturated vs saturated fats. Specifically, each double-bonded carbon is capable of making a total of four bonds, including the double bond itself, so it can only bond to two other atoms.