This is a fill-in-the-blank exercise likely related to vocabulary or common collocations in English.
Based on the context that "Everyone wants to take a picture of Kay," it implies that Kay is likely someone notable or attractive, making her a subject of interest.
A suitable word to fill the blank in sentence B, "She's a very ... girl!", would be an adjective that aligns with this implied context.
Let's assume a common adjective like 'popular' is intended.
Answer: popular