What type of agency is established when a broker is asked to show homes without a signed agreement?

The correct answer is agency by ratification. This type of agency occurs when one party acts on behalf of another without prior consent, and the actions are subsequently approved or legitimized by the other party. In the case of a broker showing homes without a signed agreement, if the seller later accepts the broker’s actions and acknowledges them, this forms an agency by ratification. The seller essentially retroactively approves the broker's actions, leading to an official agency relationship, even though no formal agreement was in place initially.

In an agency by necessity, a situation arises where one individual must act on behalf of another due to an emergency or unforeseen circumstance, which doesn't apply here since there was no necessity in showing homes without an agreement. Agency by default refers to a situation where an agency relationship exists due to a lack of any other agreed-upon representation, but it does not encompass the formalization of actions taken without a prior agreement. Agency by estoppel occurs when a principal cannot deny the existence of an agency because of their own representations and the reliance of a third party. While there could be some overlaps in scenarios, it does not fit this specific case like agency by ratification does.