Task: Question Answering
Input (English): Problem: calculate how many seconds it eill take for 4 bells to toll together again , given that they begin to toll together respectively at the intervals of 5 , 8 , 11 and 15 seconds . ? 
Options: a ) 1310 , b ) 1320 , c ) 1322 , d ) 1323 , e ) 1312
Output (English): b