Instinct is the ______ tendency that a person or animal has to b

Instinct is the ______ tendency that a person or animal has to behave or react in a particular way. (nature)
【正确答案】：natural
【题目解析】：译文：本能是一个人或动物只能用一种特殊的方式作出行为或反应的天生的倾向。本句话包含一个由that引导的定语从句，它的先行词为tendency。这里该先行词缺少形容词作修饰语。答案为natural。