Answer:
b. Run-on
Step-by-step explanation:
A run-on sentence refers to a faulty sentence in which two or more main clauses are joined without a connecting word or a punctuation mark. In this case, this is the situation we are faced with, as the sentence includes three main clause. In order to correct it, we should write the sentence in the following way:
"Last summer we traveled to Egypt. We went there to see the great pyramids. They are one of the seven wonders of the ancient world."