17. The best argument in support of this motion would be that

B is correct. In a negligence action, the plaintiff must establish four elements: duty, breach, causation, and damages. Here, the defendant's best argument among these answer choices is that the harm the plaintiff suffered is outside the scope of the plaintiff's negligence duty. Normally, defendants are liable only to foreseeable plaintiffs and for foreseeable harms. Although the loss of the trees is arguably sufficiently foreseeable harm in many jurisdictions, this is the best answer of those presented because the others are invalid options.

A is incorrect. Although the language «active cause» is not frequently used, it is also incorrect in this instance. The defendant's actions were an actual cause of the harm.

C is incorrect. The language of this answer is not the standard, most-common phrasing of negligence, and it is arguably also factually incorrect because the defendant's negligence in burning down his house would naturally and probably cause the elements to reach plaintiff's property to a greater extent, which could lead to harm to plaintiff's property.

D is incorrect. The plaintiff's damage to his trees would not be considered purely economic loss; that category pertains to damages like lost earnings and medical bills. Damages from harm to property are generally recoverable in a negligence action.