Final answer:
The unit rate is 0.56 liters per dollar.
Step-by-step explanation:
The unit rate is determined by dividing the quantity (in this case, 4 liters) by the cost (in this case, $7.19). So, the unit rate is 4 liters / $7.19, which can be simplified to 0.56 liters per dollar. Therefore, the correct answer is option a) 0.56 liters per dollar.