3. The following mistakes related to the folk culture in the area where Hanxin is located are () A. Tibetan robes are the national costumes in ①. B's traditional residence is a kiln.

Tibetan robe is the national costume of Tibetans in Qinghai-Tibet area, so A's description is wrong and accords with the meaning of the question.

The traditional houses in the Loess Plateau are caves, which have the advantages of being warm in winter and cool in summer, so B's description is correct and does not meet the meaning of the question;

The climate in Sichuan basin is humid, and people in this area like to eat spicy food, so C is correct and does not meet the meaning of the question;

The Dai people in Yunnan have a water-splashing festival, so D is correct and does not meet the meaning of the question.

So choose: a.