Task: Question Answering
Input (English): Problem: two bullet trains of equal lengths take 10 seconds and 12 seconds respectively to cross a telegraph post. if the length of each bullet train be 120 metres, in what time ( in seconds ) will they cross each other travelling in opposite direction ?
Options: a. 11 sec., b. 15 sec., c. 12 sec., d. 17 sec., e. 19 sec.
Output (English): a