Task: Question Answering
Input (English): Problem: a driver just filled the car ' s gas tank with 45 liters of gasohol , a mixture consisting of 5 % ethanol and 95 % gasoline . if the car runs best on a mixture consisting of 10 % ethanol and 90 % gasoline , how many liters of ethanol must be added into the gas tank for the car to achieve optimum performance ? 
Options: a ) 1.3 , b ) 1.7 , c ) 2.1 , d ) 2.5 , e ) 2.9
Output (English): d