Problem: george ' s car calls for 8 ounces of oil for each cylinder used . his car ' s engine has 6 cylinders . if 16 ounces of oil has already been put into the engine used , then how many additional ounces of oil are needed ? 
Options: ['a ) 16', 'b ) 48', 'c ) 64', 'd ) 32', 'e ) 8']
d