What phrase fits best where the man says, "Oh, _____ your hair cut. You look really different now, but I like it."?

The phrase "you've had" is the best fit in this context because it uses the present perfect tense, which indicates an action that has relevance to the present moment. When the man says, "Oh, you've had your hair cut," he is acknowledging that the haircut happened at some point in the past and that this action has an impact on how the person looks now. This construction emphasizes that the experience of having the haircut is still relevant to the current situation, as it has changed the person's appearance in a noticeable way.

Using the present perfect here allows for a smooth transition into expressing his reaction, "You look really different now, but I like it." This construction effectively captures the surprise and appreciation for the change, making it the most appropriate choice. Other phrases, while potentially grammatically correct in different contexts, do not convey the same immediacy or relevance to the current moment.