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.

Ex Input:
Passage: Tourism is a major industry owing to the city's climate, its beaches, and numerous tourist attractions such as Balboa Park, Belmont amusement park, San Diego Zoo, San Diego Zoo Safari Park, and SeaWorld San Diego. San Diego's Spanish and Mexican heritage is reflected in the many historic sites across the city, such as Mission San Diego de Alcala and Old Town San Diego State Historic Park. Also, the local craft brewing industry attracts an increasing number of visitors for "beer tours" and the annual San Diego Beer Week in November; San Diego has been called "America's Craft Beer Capital."

Ex Output:
What type of tours attract a large number of visitors to San Francisco?

Ex Input:
Passage: The best, worst and average case complexity refer to three different ways of measuring the time complexity (or any other complexity measure) of different inputs of the same size. Since some inputs of size n may be faster to solve than others, we define the following complexities:

Ex Output:
What are the three secondary expressions used to represent case complexity?

Ex Input:
Passage: This changed with the recent sovereign-debt crisis. The ECB always could, and through the late summer of 2011 did, purchase bonds issued by the weaker states even though it assumes, in doing so, the risk of a deteriorating balance sheet. ECB buying focused primarily on Spanish and Italian debt. Certain techniques can minimise the impact. Purchases of Italian bonds by the central bank, for example, were intended to dampen international speculation and strengthen portfolios in the private sector and also the central bank.

Ex Output:
What debt did the ECB forgive?