Task: Question Answering
Input (English): Problem: two bike riders ride in opposite directions around a circular track , starting at the same time from the same point . biker a rides at a speed of 16 kmph and biker b rides at a speed of 14 kmph . if the track has a diameter of 40 km , after how much time ( in hours ) will the two bikers meet ? 
Options: a ) 8.18 hrs . , b ) 6.18 hrs . , c ) 4.18 hrs . , d ) 1.18 hrs . , e ) 7.18 hrs .
Output (English): c