What type of agency is created when a principal agrees to honour the obligations of an unauthorised act conducted by an agent?

The correct choice is ratification because it refers to the process by which a principal approves an agent's unauthorized actions, thereby making those actions binding as if they had been authorized from the outset. When a principal ratifies an agent's unauthorized act, they accept the benefits of that act and commit to honoring the obligations created by it. This often occurs in situations where the agent acted in good faith, and the principal stands to benefit from the transaction.

Other concepts, while related to agency, do not fit the scenario as precisely. Apparent authority revolves around the appearance of the agent's authority to third parties, created by the principal's conduct, rather than an acknowledgment of unauthorized acts. Consent involves the agreement between the principal and agent about the scope of authority before any actions occur, which is distinct from the situation of ratifying a previously unauthorized act. Necessity pertains to situations where an agent must act without authorization to prevent harm or loss, which is again different from ratification. Thus, ratification is the appropriate term for a principal accepting and validating an agent's prior unauthorized actions.