This task is about creating an unanswerable question based on a given passage. Construct a question that looks relevant to the given context but is unanswerable. Following are a few suggestions about how to create unanswerable questions:
(i) create questions which require satisfying a constraint that is not mentioned in the passage
(ii) create questions which require information beyond what is provided in the passage in order to answer
(iii) replace an existing entity, number, date mentioned in the passage with other entity, number, date and use it in the question
(iv) create a question which is answerable from the passage and then replace one or two words by their antonyms or insert/remove negation words to make it unanswerable.

Passage: The gospels of Matthew and Luke in the New Testament describe Mary as a virgin (Greek: , parthenos) and Christians believe that she conceived her son while a virgin by the Holy Spirit. This took place when she was already betrothed to Joseph and was awaiting the concluding rite of marriage, the formal home-taking ceremony. She married Joseph and accompanied him to Bethlehem, where Jesus was born. According to ancient Jewish custom, Mary could have been betrothed at about 12, however, there is no direct evidence of Mary's age at betrothal or in pregnancy. The term "betrothal" is an awkward translation of kiddushin; according to the Jewish law those called "betrothed" were actually husband and wife.
How old was Mary when she met Joseph?