​Horizontal contracts often

A) ​Increase competition between substitute products
B) Eliminate competition between substitute products
C) Do not change the competition between substitute products
D) ​None of the above

Horizontal contracts are agreements between firms that are at the same level of the supply chain, such as two competing retailers or two suppliers of a single component. Such contracts often include clauses that limit competition between the parties by prohibiting one party from selling to or buying from a competitor, and these clauses can have the effect of reducing competition between substitute products. Therefore, the correct answer is B, which states that horizontal contracts eliminate competition between substitute products.