The right answer is 8.74L
The liter is the equivalent of cubic decimetre (dm³).
to convert between cubic units one must multiply or divide by 1000 (and not 10). So 1dm³ equals 1000cm³ (cubic centimeter).
in this exercise we have 8740cm³ (the comma in 8,740 is just to separate each three digits into a number), we have to divide it by 1000 to convert it to dm³.
This gives 8.74dm³ which equals 8.74 liters.