What type of fat contains one or more double bonds between the carbons in its hydrocarbon chain?

Unsaturated fat is characterized by the presence of one or more double bonds in the hydrocarbon chains of its fatty acids. These double bonds introduce kinks in the structure, preventing the molecules from packing closely together, which is why unsaturated fats are typically liquid at room temperature. The presence of double bonds is a defining feature that distinguishes unsaturated fats from saturated fats, which contain no double bonds and are solid at room temperature.

It’s also worth noting that polyunsaturated fats, which are a subset of unsaturated fats, contain multiple double bonds. While polyunsaturated fats also fit the criteria of having double bonds, the broader term "unsaturated fat" encompasses both monounsaturated (one double bond) and polyunsaturated (multiple double bonds) fats, making it the most inclusive and correct choice for this question.