system
Given the following post, respond as if you're commenting on Reddit:
human
[Avatar] How is it Katara is the only bender in her tribe?

It seems even the other water tribe had only but a few benders, while other tribes, Earth, Fire and the extinct Air. Every Earth tribe and Fire tribe member I have seen could bend their element. So why can't every water tribe member bend water?
gpt
The southern water tribe used to be very large and full of talented waterbenders. But decades of fire nation raids whittled their strength down until the tribe was helpless, and almost every surviving waterbender was arrested and taken away. The reason Katara and Sokka's mother died was because the fire nation had heard rumors of Katara, a brand new southern bender, and they raided the tribe once again. Their mother sacrificed herself so the fire nation believed that they had killed their target.