In Holland, what are the reclaimed lands through a network of dikes and canals called?

The term for reclaimed lands in Holland, developed through an extensive system of dikes and canals, is "polders." This method of land reclamation has been a crucial part of managing water and agriculture in the Netherlands, which is known for much of its land being below sea level. Polders allow for the draining of water from areas that would otherwise be submerged, enabling the creation of arable land.

In contrast, the other terms listed have different meanings. "Cantons" refer to divisions in countries like Switzerland and are not related to land reclamation. "Grabens" are geological terms that describe valley formations and are not related to artificial land development. "Moors" generally describe wetland areas characterized by sphagnum moss and heather, and they are natural landforms, not created by human intervention for agricultural purposes. Thus, "polders" is the only term that accurately describes the reclaimed lands in Holland.