Which of these is a simple sentence and why? 1) Karen and David arrived at the airport at 3:35 p.pm and took a taxi to their hotel. 2) I went to the airport, but I was too late to meet them. 3) When I realized I was too late, I called David's cell phone and made arrangements to meet them in town. 4) I got to the airport late because the traffic was so terrible.

Look at the types of simple sentences at this site.

http://www.eslbee.com/sentences.htm

A simple sentence is a sentence that contains one independent clause and expresses a complete thought. Let's analyze each option to determine which one fits this criteria.

1) "Karen and David arrived at the airport at 3:35 p.m and took a taxi to their hotel."
This sentence is not a simple sentence because it includes two independent clauses ("Karen and David arrived at the airport at 3:35 p.m" and "and took a taxi to their hotel") joined by the coordinating conjunction "and." It is a compound sentence.

2) "I went to the airport, but I was too late to meet them."
This sentence is not a simple sentence either. It is a compound sentence that consists of two independent clauses ("I went to the airport" and "but I was too late to meet them") joined together by the coordinating conjunction "but."

3) "When I realized I was too late, I called David's cell phone and made arrangements to meet them in town."
This sentence is also not a simple sentence as it contains two independent clauses. The first independent clause is "When I realized I was too late" and the second independent clause is "I called David's cell phone and made arrangements to meet them in town." These clauses are joined by the coordinating conjunction "and."

4) "I got to the airport late because the traffic was so terrible."
This sentence is a simple sentence because it contains only one independent clause, "I got to the airport late because the traffic was so terrible." It expresses a complete thought, and it does not contain any coordinating conjunctions to join multiple independent clauses.

Therefore, option 4, "I got to the airport late because the traffic was so terrible," is a simple sentence because it meets the criteria of having only one independent clause and expressing a complete thought.