The sentence "I can't find the application forms. Excuse me, do you know _______?" requires an indirect question. In an indirect question, the word order is typically wh-word + subject + verb, not the inverted verb + subject order of a direct question. Let's look at the options: "are they where" - This is grammatically incorrect. "where are they" - This is the structure for a direct question (e.g., "Where are they?"). "where they are" - This follows the correct structure for an indirect question (wh-word + subject + verb). Therefore, the correct way to complete the sentence is "do you know where they are?". The correct option is: where they are