Step 1: What is asked.
We need the host city of the 25th Summer Deaflympics 2025.
Step 2: About the Deaflympics.
The Deaflympics is a global multi sport event for deaf athletes, recognised at the international level.
Step 3: The host.
The 25th Summer Deaflympics in 2025 were hosted in Tokyo, Japan, which used its many world class sports venues.
Step 4: Note on the key.
The given answer key marks Paris, but the correct host of the 2025 Summer Deaflympics is Tokyo, so the right option is Tokyo.
Step 5: Remove others.
London, Paris, and Barcelona were not the host of this edition.
Step 6: Conclusion.
So the 25th Summer Deaflympics were held in Tokyo.
Answer: Tokyo