What two rivers define the borders of the Sherry Triangle?

The two rivers that define the borders of the Sherry Triangle are indeed the Guadalquivir and the Guadalete Rivers. This triangular area, known as the Sherry Triangle, encompasses the primary regions of Jerez, Sanlúcar de Barrameda, and El Puerto de Santa María, which are the main production areas for Sherry wine.

The Guadalquivir River runs through southern Spain and has a significant influence on the climate and viticulture of the region, while the Guadalete River flows into the Guadalquivir and contributes to the terroir that is essential for growing the Palomino grape, the main grape variety used in Sherry production.

The other options include rivers that are not associated with the Sherry Triangle's geographical boundaries, making them irrelevant to the defining features of this important wine-producing area.