The correct answers are A more attentive waiter would have noticed my empty water glass., But for the exquisite chocolate soufflé, the entire evening would have been a total disaster., and Without that distracting live band, we might actually have enjoyed our conversation.

Implied conditionals express hypothetical situations without using a standard "if" clause. Instead, they use noun phrases (like A more attentive waiter...), or prepositional phrases (like But for... or Without...).

The sentence starting with "If the chef..." is grammatically correct but uses an explicit "if" clause, so it is not an implied conditional.

The sentence starting with "The manager apologized..." contains a fatal tense mismatch: a past tense action ("apologized") paired with a future real result ("will leave") after "otherwise." It should be "otherwise, I would have left."