The sentence that correctly combines the two sentences into a sentence with a compound verb is C. The settlers moved into the unknown and left the familiar behind.
Explanation:
Whenever a subject has two or more verbs, it is said that the subject thas a <u>compound verb</u>. In this case, the subject <em>settlers </em>have two verbs -<em>moved </em>and <em>left</em>. Therefore, option C is the correct answer.