A boy rode his bicycle northward, then turned left and rode 1 km, then turned left again and rode 2 km. After these movements, he found himself 1 km west of his starting point. How far did he initially ride northward?
- A. 1 km
- B. 2 km
- C. 3 km
- D. 5 km
- 2 km
Please select one of the options to reveal the correct answer.