The answer to your question would be that the revision that most effectively corrects the dangling modifier in the sentence is the following one: Tempted by the delicious-looking chocolate, I let my diet go out the window.
A dangling modifier occurs when the subject being modified, or described by the modifier, does not actually appear in the sentence. As this modifier has no subject, it is considered to be "dangling". In the original sentence "tempted by the delicous-looking chocolate" should be describing a person who is tempted by this chocolate. However, it is not describing anything, it is just dangling. It may look as if it was modifying "the diet", but diets have no volition, they can't be tempted by anything. Therefore, the solution to this problem is to add a subject and ensure that the modiifer goes directly next to the subject that it is modifying, just as the revised version of the sentence suggests.