Which type of fat has a fully hydrogenated carbon backbone with no double bonds?

Saturated fat is characterized by having a fully hydrogenated carbon backbone, which means that all carbon atoms in the fatty acid chain are single-bonded to each other and are fully saturated with hydrogen atoms. This structure results in no double bonds between carbon atoms. As a result, saturated fats are typically solid at room temperature and can be found in animal products and some plant oils.

The other options refer to different types of fat with varying structures. Monounsaturated fat contains one double bond in its carbon chain, which introduces a kink in its molecular structure, whereas polyunsaturated fat has two or more double bonds. Trans fats, although they can sometimes adopt a straight structure similar to saturated fats due to their arrangement, also contain double bonds in their structure. Thus, among all the choices, saturated fat clearly fits the criteria of having a fully hydrogenated carbon backbone with no double bonds.