Task: Question Answering
Input (English): Problem: a box measuring 90 inches long by 45 inches wide by 9 inches deep is to be filled entirely with identical cubes . no space is to be left unfilled . what is the smallest number of cubes that can accomplish this objective ? 
Options: a ) 17 , b ) 18 , c ) 50 , d ) 108 , e ) 864
Output (English): c