Which of the following is a simple sentence?

A. Karen and David arrived at the airport at 3:35 p.m. and took a taxi to their hotel.

B. I went to the airport, but I was too late to meet them.

C. When I realized I was too late, I called David's cell phone and made arrangements to meet them in town.

D. I got to the airport late because the traffic was so terrible.

2 answers

D is the simple sentence.
A look at the and
B see the comma...
C see the comma
A is the simple sentence with a compound subject and compound verb.

subject Karen and David
predicate arrived and took

B. is a compound sentence, two sentences joined by "but"

C. and D are complex sentences.
When I realized..... is an adverb clause
because the traffic..... is also an adverb clause.