Help the clumsy baker complete the tragic tale of the exploding dessert by selecting the correct phrase.

The giant five-tier wedding cake suddenly collapsed, ____ months of careful planning in a matter of seconds.

The correct answer is ruining.

We can use a present participle (-ing) clause at the end of a sentence to express the result or consequence of the action in the main clause. "Ruined" would require a conjunction (like and ruined), while "having ruined" incorrectly implies the ruining happened before the collapse.