What course were the speaker’s father and mother both interested in? They were both interested in______.

My mother told me how she and my father got together when they were young. (11) My mother was interested in a young man in her English literature class at college, but she was too shy to let him know. One day she heard that he was on his way to the library for a certain book. (12)She rushed to the library, found the book and stuck in it a letter from her mother. "Why would he want to read a letter from grandma?" I asked."Of course he wouldn’t," mom said, "(13)but if he’s any kind of gentleman, he’ll return it to me. (14)My dormitory number was on the envelope." The next day he appeared with the letter and asked my mother out on a date. (15)The book was Great Expectations. And that’s how my father and mother fell in love.