TASK DEFINITION: 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.
PROBLEM: Passage: The effects of local surface low pressure are extremely limited because upper-level subsidence still continues to block any form of air ascent. Also, to be protected against rain-bearing weather systems by the atmospheric circulation itself, the desert is made even drier by his geographical configuration and location. Indeed, the extreme aridity of the Sahara can't be only explained by the subtropical high pressure. The Atlas Mountains, found in Algeria, Morocco and Tunisia also help to enhance the aridity of the northern part of the desert. These major mountain ranges act as a barrier causing a strong rain shadow effect on the leeward side by dropping much of the humidity brought by atmospheric disturbances along the polar front which affects the surrounding Mediterranean climates.

SOLUTION: what is blocked buy the surface low pressure?

PROBLEM: Passage: During World War II, Hitler's Generalplan Ost (general plan for the East) entailed killing, deporting, or enslaving the Slavic and Jewish population of occupied Eastern Europe to create Lebensraum (living space) for German settlers. The Nazi Hunger Plan and Generalplan Ost would have led to the starvation of 80 million people in the Soviet Union. These partially fulfilled plans resulted in the deaths of an estimated 19.3 million civilians and prisoners of war.

SOLUTION: How many prisoners of war were supposed to die from the Hunger Plan?

PROBLEM: Passage: The instrument was primarily used in an ensemble setting well into the 1930s, and although the fad died out at the beginning of the 1930s, the instruments that were developed for the orchestra found a new home in bluegrass. The famous Lloyd Loar Master Model from Gibson (1923) was designed to boost the flagging interest in mandolin ensembles, with little success. However, The "Loar" became the defining instrument of bluegrass music when Bill Monroe purchased F-5 S/N 73987 in a Florida barbershop in 1943 and popularized it as his main instrument.

SOLUTION:
The setting the mandolin was used in until the 1940's was?