Explanation

Even though the range of costs ($44 to $50) is fairly small, there is still more than one possibility. A good way to work this out is to start with the simplest scenario: 3 adults and 3 children. Their tickets would cost 3(9) + 3(6) = $45. That’s in the range, so it’s one possibility.

Since children’s tickets are cheaper, you don’t want to add more children to the mix (4 children, 2 adults will give you too small a total), but try switching out 1 child for 1 adult.

For 4 adults and 2 children, tickets would cost 4(9) + 2(6) = $48. Thus, Quantity A and Quantity B could be equal, or Quantity B could be greater, so the relationship cannot be determined from the information given.

Hence option D is correct!