Which of the following is a complex sentence? A. As Jake was reading the letter from June yet again, the flight attendant coughed gently to get his attention. B. I simply cannot make heads or tails of rap lyrics, but I suppose I'm just too old to understand them. C. Check out the editorial page in today's paper and you'll notice the piece by Oscar Lewis. D. I would like to visit the Kinshasa, but I understand the city is unsafe for foreigners.