Review Question - QID 214751

A 42-year-old woman presents to her primary care physician with a 6-week history of intermittent chest pain and difficulty swallowing. She says that she first noticed the difficulty with swallowing while she was drinking a cocktail at dinner but that it has since progressed to where she has difficulty swallowing almost everything. In addition, she complains of worsening heartburn as well as intermittent vomiting with pieces of undigested food. She has not noticed any other symptoms and says that she has been able to continue all of her normal activities. Which of the following are the best diagnostic test and most likely finding for this patient?