Answer:
contract combinations and conspiracy to restrain trades
Step-by-step explanation:
Interstate commerce according to the constitution of the U.S it is a trade or exchange of goods and services or flow of traffic that involves more than one state. it can be said to be a trade/commercial transaction that goes/crosses a state boundary.
The commercial activities involving states and even countries are regulated by congress as stated in the constitution under the commerce clause and this tends to restrict monopolistic powers by states involved in commercial activities across borders.and the Sherman Anti-Trust Act also restricts monopolist competition and reduces economic competition
hence having congress control Interstate trades involving restraining of state powers and having combined contracts