Final answer:
The listing agreement for Seller A's property would be terminated if the property is taken by eminent domain for a highway since the seller can no longer fulfill the terms of the sale after the government acquires the property and provides just compensation.
Step-by-step explanation:
When Seller A's property is taken by the state through eminent domain for public use such as a highway, the existing listing agreement for the sale of the property would typically be terminated. This is because the contract for sale can no longer be fulfilled due to the compulsory acquisition of the property by the government. According to the Takings Clause of the Fifth Amendment, the government is authorized to take private property for public use, provided that the owner is given just compensation. In the context of a real estate sale, once the property is seized and just compensation is paid, Seller A no longer has the title or control required to sell the property, thus nullifying the listing agreement. Additionally, it is important to note that any disputes over the amount of compensation or the use of eminent domain itself could lead to legal proceedings.