Given the task definition and input, reply with output. This task is about reading the given passage and construct a question about the information present in the passage. Construct a question in such a way that (i) it is unambiguous, (ii) it is answerable from the passage, (iii) its answer is unique (iv) its answer is a continuous text span from the paragraph. Avoid creating questions that (i) can be answered correctly without actually understanding the paragraph and (ii) uses same words or phrases given in the passage.

A samurai could divorce his wife for a variety of reasons with approval from a superior, but divorce was, while not entirely nonexistent, a rare event. A wife's failure to produce a son was cause for divorce, but adoption of a male heir was considered an acceptable alternative to divorce. A samurai could divorce for personal reasons, even if he simply did not like his wife, but this was generally avoided as it would embarrass the person who had arranged the marriage. A woman could also arrange a divorce, although it would generally take the form of the samurai divorcing her. After a divorce samurai had to return the betrothal money, which often prevented divorces.
How common was divorce for samurai?