Which of the following is a characteristic of unglazed porcelain tiles?

Unglazed porcelain tiles are indeed typically more susceptible to staining due to their porous nature compared to glazed options. This characteristic is significant because unglazed tiles absorb moisture and can trap dirt and other contaminants if not properly maintained. To mitigate this issue, it's common practice to seal unglazed porcelain tiles to enhance their resistance to staining and make cleaning more manageable. Sealing creates a protective barrier that helps keep the surface clean and prolongs the life of the tiles.

The other choices do not accurately represent the characteristics of unglazed porcelain tiles. For instance, they are not more porous than glazed tiles, which are designed with a glass-like surface that helps prevent moisture absorption. Additionally, unglazed tiles come in a wide variety of colors and textures, often providing as much or more aesthetic versatility as their glazed counterparts. Finally, unglazed porcelain tiles are often celebrated for their durability, often scoring higher on hardness and resistance compared to glazed tiles. Thus, sealing is indeed a key aspect of their maintenance, making it an important distinction in understanding their properties and care requirements.