"Businesses that engage in supply chain management work to establish long-term relationships with a small number of very capable suppliers who are called ."

The correct answer is: tier-one suppliers.

Explanation:

The first level suppliers are all those autonomous companies or strategic commercial units that carry out value-added, operational or management activities in the commercial processes, generating a specific performance for a particular client or market. For their part, the support members are the companies that simply provide the resources, knowledge and equipment for the supply chain primary. For example, support companies include carriers, banks that lend money, the owner of the building that provides warehouse space, companies that provide production equipment, etc. They are suppliers with the minimum level of integration.

First-tier suppliers compete strongly with each other for the market. There are hundreds of them; Some are very large companies with annual sales of billions of dollars. Some of the top-level suppliers also operate at the lower levels of the chain, either through vertical integration, or supplying parts to their rivals in the first level.

its kinda hard to answer this when we dont have all the information that we need.