Correct answer: (c) Feldspars

Explanation:

The feldspars are most abundant aluminosilicate minerals in the Earth surface. The silicon atoms and aluminium atoms occupy the centres of interlinked tetrahedra of SiO₄^4- and AlO₄^5-. These tetrahedra connect at each corner to other tetrahedra forming an intricate, three dimensional, negatively charged framework. The sodium cations sit within the voids in this structure.