Which best describes the underlined words in this sentence? they were staying at a cozy little cabin in the mountains.
a. simple predicate
b. complete predicate
c. compound verb

In the question asked, since the underlined word is undetermined. If the underline word is “were staying” only this would probably mean only a simple predicate. Notice that the phrase structure is only composed of a linking verb and the word verb or rather gerund “staying”. Contrarily, if the underlined word is “were staying at a cozy little cabin in the mountains”, this would indicate a complete predicate. Which entails the linking verb the verb and the situation which describes the sentence.