You did not include options in your question, but based on the meaning of the word cryptic, your answer will be 'A HIDDEN MEANING'.
When you say that something is cryptic, it means that, that thing has a meaning that is mysterious or obscure.
From the way the word was used in the given sentence, it means that the message the teacher was passing across about the test is hidden, it was not understood by any of the students.
"We know you say you have a lot of money, so give us just a little and we will leave you alone." I chose this cause it sounded like they asked for a hundred pounds when they could have asked for more, and sounds like they are coming back. Hope this helps!
