Explanation:

- Primary industries involve the extraction and harvesting of natural resources. Examples include agriculture, fishing, and mining.

- Secondary industries pertain to manufacturing and processing. They transform raw materials into finished products. Oil refineries and sugar mills fall under this category as they process raw materials into usable products.

- Tertiary industries involve services rather than goods. These include retail, transport, and other services like banking.

- The option "None of these" implies that the industry doesn't fit into any standard category which is not the case here.

Your highlighted answer:

- Option 2: Secondary