You should have noted that the diagram showed a carwash system, and that approximately half of the possible answers in the list were numbers. For the first three questions, it was likely from the grammar of the sentences that the answers were numbers relating to quantity of water. The diagram alone did not help us to identify what questions 14 and 15 were, but you should have been considering prepositions and sequencing words. In the recording, the speaker actually said that ‘water is simply expelled to the sand trap’ – number 14- ‘then transferred immediately to the treatment tank’ – which therefore must have been the answer to question 15. With question 16, we could again assume that the answer was a number, as we are asked to compare something to a number already shown – 35 litres.