Task: Question Answering
Input (English): Question: For my anniversary, I decided to surprise my wife. Since she is a voracious reader, I decided to collect a lot of books for her. On the first day of the month, I bought one book, on the second, I bought two and on the third, I bought three. This process went on till the anniversary and on the day, I had 181 books with me to gift her.
Can you calculate, on which day is our anniversary?

 Option A: 31

 Option B: 18

 Option C: 23

 Option D: 33

 Option E: 25
Output (English): Option B