Final answer:
The provided argument is fallacious since it incorrectly extends the property of some desserts being low fat to all desserts, neglecting examples like buttercream cake which is high in fat.
Step-by-step explanation:
The argument provided is an example of a logical fallacy, particularly a hasty generalization. The argument suggests that because all desserts are sweet foods, and some sweet foods are low fat, then all desserts must be low fat. This is an invalid conclusion because being a sweet food does not inherently mean that the item is low fat.
To illustrate why the argument is flawed, consider the counterexample of buttercream cake. A buttercream cake is inherently a dessert and is a sweet food. However, due to the high-fat content in buttercream icing, it is not a low-fat food item. This demonstrates that not all desserts are low fat, thereby making the argument incorrect.
It is important to analyze arguments critically and discern whether they are logically sound or whether they contain logical errors such as the one presented in this argument.