An article in the Wall Street Journal discussing the nickel market contained the following: The sharp rise in nickel prices demonstrates how even a slight shift in demand and supply can roil tiny commodity markets like those for nickel, orange juice and cocoa. Nickel is roughly a $12 billion market, while the crude-oil market is $280 billion, based on the open interest on major exchanges.

a. What does the article mean by a market being "roiled"?

b. Given this information about "tiny commodity markets," would it be more or less valuable for participants in these markets to have futures contracts available to them than it would be for participants in larger commodity markets, such as the market for oil?

c. What does the article mean by "open interest on major exchanges"? Why would this be a measure of the size of a market in a commodity?