Task: Question Answering
Input (English): Problem: a certain clock marks every hour by striking a number of times equal to the hour , and the time required for a stroke is exactly equal to the time interval between strokes . at 6 : 00 the time lapse between the beginning of the first stroke and the end of the last stroke is 66 seconds . at 12 : 00 , how many seconds elapse between the beginning of the first stroke and the end of the last stroke ? 
Options: a ) a . 138 , b ) b . 50 , c ) c . 48 , d ) d . 46 , e ) e . 44
Output (English): a