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.
Answer:
a passage of time while studying
Explanation:
In the introduction to his book great astronomers, Robert stawell all develop and refine the central idea in his book by providing biographical information by specific astronomers and their discoveries. With it, he also connect it to their contributions to the history of great men
hope this helps
Saved as it's collective, he's collecting it
