A better assessment of the strengths of the two tests would be to show the number of problems a child can reasonably do in a set amount of time from each, and see how many skills the child has to master to do well on those problems.
1) The problem specifies the number of seats in each vehicle type, not the number of passengers it can carry. Does the correct answer presume that you have added a driver for each vehicle when calculating the total number of people transported?
2) If you need to make room for drivers, are the teachers driving a vehicle? So is the number of people in the vehicles equal to 69 students plus 3 teachers plus a driver for each vehicle, or three less than that total since the teachers could double as drivers.
Admittedly, the three "correct" answers all exceed any the total number of students, teachers, and drivers, but how much valuable time might be wasted by a student who thinks about this issue?
In addition, there is a third issue:
Who is driving the vehicles? The problem only mentions three adults (i.e., the three teachers), but no combination of vehicles can accommodate all the teachers and students with only three vehicles. So a student who is thinking critically might well conclude that it is impossible for all the students to be taken on the field trip.