If igneous rock forms above ground after a volcanic eruption

Silica, sio2, is formed on silicon as an electrically insulating layer for microelectronic devices. silica is formed when silicon is exposed to o2 gas at an elevated temperature. at 900˚c, it takes 90 minutes for the oxygen to diffuse from the surface to form a 0.06 micron (0.06 x 10-6 m) thick layer of sio2 on

The answer for #3 is c but i don't know why

If two atoms are bonded to a central atom with no lone pairs, how will they be arranged