What is a key difference between voluntary and involuntary liens?

The correct answer highlights a fundamental aspect of how voluntary liens are established. Voluntary liens arise when a property owner willingly enters into an agreement to secure a debt, which is often done through a mortgage or other loan agreements. This agreement signifies that the owner is aware of and consents to the lien being placed on their property as collateral.

In contrast, involuntary liens occur without the owner's consent, typically arising due to legal actions such as unpaid taxes or court judgments. Though some options might allude to legal processes or sizes of liens, the essence of the matter lies in the owner's agreement or lack thereof regarding the lien. Therefore, option B accurately captures this critical distinction.