alternative pleading在Wikipedia给出的英文解释为：

Alternative pleading (or pleading in the alternative) is the legal term in the law of the United States for a form of pleading that permits a party in a court action to argue multiple possibilities that may be mutually exclusive by making use of legal fiction.

（选择诉答是美国法律中的法律术语，指一种诉状形式，它允许法院诉讼中的当事方通过使用拟制来辩论可能相互排斥的多种可能性。）

《元照英美法词典》中给出的对应中文为：选择诉答

〈美〉

指诉答人可以提出两种或两种以上并不必然一致的请求或答辩。如果诉答中的陈述是替代性的，且其中之一是充分的，那么诉答不会因为另一或其他陈述的不充分性而被认定为不充分。这种诉答曾受禁止，但现在在联邦及州的民事诉讼规则中都是受到认可的。 

选择诉答的目的：

The purpose of alternative pleading is to allow the pleader to seek relief when the pleader is uncertain about the facts that will be developed during the course of an action as well as to present several alternative explanations of the evidence to the fact finder. For example, a plaintiff in a car accident may allege that the defendant was negligent and committed battery. While these two theories are inconsistent, the plaintiff may not know during the pleading stage whether the defendant ran into the plaintiff intentionally.

Both the plaintiff and defendant may plead in the alternative. 

PS:美国的民事起诉标准经历了三个发展阶段：普通法诉答(common law pleading)、事实诉答或法典诉答(fact pleading or code pleading)以及通知诉答(notice pleading)。