An industry is

An industry is

  1. A group of firms producing differentiated products
  2. A group of firms producing distinct commodities
  3. A group of firms producing related goods ✓
  4. A group of firms producing unrelated goods

Explanation

This answer correctly explains the economic concept. Economics studies how people make choices about limited resources.

The other options describe different economic ideas or situations. They don’t fit what this question asks.

Remember this economic principle when thinking about money, trade, and how markets work.