CPI tracks market-purchased goods and services

Steps:

• CPI measures price changes for a basket of consumer goods and services bought in the market.
• Identify items typically in the basket: food, apparel, electronics—all market transactions.
• Exclude non-market items like homemade goods, as no purchase price exists.
• Compare options: A, B, D involve purchases; C does not.

Why C is correct:

• CPI includes only priced market transactions; homemade clothes have no market price, per BLS methodology.

Why the others are wrong:

• A: Cooking oil is a standard food item in the CPI food-at-home category.
• B: Milk is a core dairy product routinely tracked in CPI food prices.
• D: Mobile phones are consumer durables included in CPI electronics and communication.

Final answer: C