For an intermediary transaction to occur, how many companies must be involved?

In the context of agency law, an intermediary transaction refers to a scenario where a licensed real estate broker represents both the buyer and the seller in a transaction, creating a dual agency situation. For this type of transaction to take place, only one brokerage firm or company is involved that acts as the intermediary between the parties. The brokerage must have established the necessary agreements to facilitate this representation, ensuring both parties understand and consent to the dual role the broker is undertaking.

Therefore, the correct answer highlights that just one company can handle the intermediary role, serving both sides in the transaction. While involving two companies might provide the scenario for separate representation, it does not align with the definition of an intermediary transaction, which emphasizes the single brokerage's capacity to represent multiple clients simultaneously.

Other options do not accurately reflect the nature of intermediary transactions, as they either suggest involvement of multiple companies or none at all, which does not align with the principles governing these types of real estate dealings.