Which type of defence involves admitting to and justifying a particular action?

The appropriate answer is indeed the concept of confession and avoidance. This type of defense occurs when a defendant acknowledges the truth of the allegations made against them but offers justifications or excuses that negate the legal consequences of those actions.

For instance, a defendant may admit to having committed an act that caused harm but argues that their actions were necessary under the circumstances or were conducted in a manner that legally absolves them of liability. By admitting to the act while simultaneously providing a legal basis for the justification, the defendant seeks to avoid the legal repercussions normally associated with the conduct.

Other options presented are distinct concepts within legal practice. Traverse, for example, involves denying the claims of the plaintiff and often requires the defendant to put forward their own version of events. A plea in abatement is utilized to argue that the case should be dismissed or paused due to specific procedural reasons rather than addressing the merits of the case itself. Objection in point of law refers to disputing the legal basis of an opponent's argument but does not inherently involve an admission of wrongdoing or justification.

Thus, confession and avoidance is correctly identified as the defense mechanism that involves acknowledging an action while providing legal justification for it.