Final answer:
The question lacks sufficient details, such as the car's fuel economy, to calculate the gallons of gas used by Mr. and Mrs. Smith. Hence, the correct answer is 'C. Not enough information is given'.
Step-by-step explanation:
The question provided does not contain enough information to determine the amount of gasoline used. To calculate the number of gallons of gas used by Mr. and Mrs.
Smith during their trip, we would need additional information such as the car's fuel economy (miles per gallon), or at least an average figure for this type of vehicle to estimate the usage.
Without the fuel economy information or an average fuel consumption rate for this car model, we cannot accurately answer the question of how many gallons were used.
Therefore, the correct answer is C. Not enough information is given.