Why is glazing applied to fired clay products such as tiles, sanitary ware, and tableware? (Consider appearance, resistance to weathering, and protection from chemical attack.)

Introduction / Context:
Glazing is a vitreous coating fused onto a ceramic body during firing. It affects aesthetics and performance of clay products used in buildings and sanitation. This question probes the full set of reasons glazing is specified in practice.

Given Data / Assumptions:

• Glaze produces a glassy, smooth surface.
• It can seal pores, reducing moisture uptake and staining.
• It improves resistance to weathering and many household/industrial chemicals.

Concept / Approach:
The functions of a glaze encompass both decorative and protective roles: color/shine, reduced porosity, and chemical/weather resistance. Hence, the inclusive option 'All of the above' best describes why glazing is used widely on tiles and sanitary ware.

Step-by-Step Solution:

Verification / Alternative check:
Standards for wall/floor tiles and sanitary ware measure water absorption and chemical resistance, both enhanced by appropriate glazing systems.

Why Other Options Are Wrong:

• Any single reason alone is incomplete; glazing is chosen for a combined performance-and-appearance package.

Common Pitfalls:
Assuming all glazes are equally chemical-resistant; overlooking that improper firing or crazing can compromise protection.

Final Answer:
All of the above