Please choose the correct ending to complete the given sentence: Finance and Business: [header] How to buy commodities [title] Familiarize yourself with the concept of commodities. [step] A commodity is simply a good that is interchangeable with other commodities of the same type, and that is usually produced and sold by many different companies. For example, a barrel of oil of one particular type, such as brent crude, is the same product regardless of who makes it.

Ending1: As such, prices fluctuate frequently over time, especially when you import stocks. [substeps] Prices and locations in exchange for commodities often change, and so it's critical to understand the broad concepts of " commodity exchange ", such as " u.s. Ending2: The price of oil is one of the main indicators of a commodity being sold. Conversely, its cost is one of the main indicators. Ending3: [title] Be aware of the disadvantages of purchasing commodities. [step] A commodities merchant publicly sells commodities via trade on behalf of himself and a buyer. Ending4: [substeps] This is opposed to a consumer product like a computer or automobile, for example. These products differ dramatically between producers and cannot be easily exchanged for one another.

Answer format: ending1/ending2/ending3/ending4