Which numbered sentence is the topic sentence? (1) The other day I had to ride on two different airlines. Early in the morning I got on a flight from San Francisco to Detroit. The plane was luxurious. (2) It had leather seats, a delicious breakfast, and courteous flight attendants who took care of our every need. The flight I boarded in the afternoon, however, was quite a contrast. (3) This plane had only twelve people, had no flight attendants, and was littered with newspapers, dirty cups, and napkins. (4) It is strange how some airlines can be so different.