Step 1: Understanding the Concept:
An agro-based industry uses agricultural produce as its main raw material.
Step 2: Classify each option:
Cotton Textile Industry uses raw cotton, a farm produce, as its principal raw material — an agro-based industry. Iron & Steel is mineral-based (iron ore); Chemical industry is often mineral/petro-based; Cement industry is mineral-based (limestone).
Step 3: Final Answer:
\[ \boxed{\text{Cotton Textile Industry}} \]