Which of the following best describes the unilateral nature of an option contract?

The correct answer emphasizes that, in a unilateral option contract, only one party is obligated to perform. This is a foundational characteristic of such contracts. In the context of real estate, when one party (the option holder) pays for the right to purchase property at a predetermined price within a specified period, the obligation to buy rests solely on them, while the other party (the option grantor) is not required to do anything unless the option is exercised.

This singular obligation contrasts with contracts that involve mutual commitments where both parties have responsibilities to each other. Specifically, a unilateral option allows the party who holds the option the freedom to choose whether or not to go through with the purchase, without forcing the other party to participate in any definitive action unless the option is exercised.

In addition, the other options mention aspects such as mutual agreements or written contracts, which, while relevant in some contexts, do not directly capture the essence of the unilateral nature of an option contract as clearly as the idea that only one party is bound to perform.