Which one of the following is also known as Dry ice in its solid form?

Solid carbon dioxide (CO₂) is commonly known as 'dry ice.' At normal atmospheric pressure, solid CO₂ sublimes directly from solid to gas without passing through the liquid phase at temperatures above −78.5°C, leaving no liquid residue—hence the name 'dry ice.' It is widely used as a cooling agent, in fog effects, and in food preservation and transport. SiO₂ is silica (sand/quartz), CaO is quicklime, and MgO is magnesia—none of which are called dry ice.