According to the types of related assets, futures can be divided into commodity futures and financial futures. Commodity futures refer to futures contracts with physical commodities as the subject matter, so A- soybean, B- crude oil and C- steel all belong to futures with specific commodities as the subject matter; The interest rate as the subject matter belongs to the subject matter of financial futures, so item B does not belong to the subject matter of commodity futures. So the answer is B.