Dry ice is:

Solid carbon dioxide

The correct answer is Option (3) → Solid carbon dioxide

Dry ice is the solid form of carbon dioxide (CO₂). It is called "dry" because it sublimates directly from solid to gas without forming liquid.

Option 1: Lead monoxide - Lead monoxide (PbO) is a chemical compound of lead and oxygen. It is not related to carbon dioxide and has no connection with dry ice.

Option 2: Silicon carbide - Silicon carbide (SiC) is a hard compound used as an abrasive and in semiconductors. It is unrelated to carbon dioxide and not dry ice.

Option 3: Solid carbon dioxide -- Dry ice is the solid form of CO₂. At atmospheric pressure, it sublimates directly to gas without melting. This matches the definition of dry ice.

Option 4: Glacier ice-  Glacier ice is frozen water (solid H₂O). Dry ice is not water ice.