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: While its fellow Canadian broadcasters converted most of their transmitters to digital by the Canadian digital television transition deadline of August 31, 2011, CBC converted only about half of the analogue transmitters in mandatory areas to digital (15 of 28 markets with CBC Television stations, and 14 of 28 markets with Télévision de Radio-Canada stations). Due to financial difficulties reported by the corporation, the corporation published digital transition plans for none of its analogue retransmitters in mandatory markets to be converted to digital by the deadline. Under this plan, communities that receive analogue signals by rebroadcast transmitters in mandatory markets would lose their over-the-air signals as of the deadline. Rebroadcast transmitters account for 23 of the 48 CBC and Radio-Canada transmitters in mandatory markets. Mandatory markets losing both CBC and Radio-Canada over-the-air signals include London, Ontario (metropolitan area population 457,000) and Saskatoon, Saskatchewan (metro area population 257,000). In both of those markets, the corporation's television transmitters are the only ones that were not planned to be converted to digital by the deadline.

SOLUTION: The CBC petitioned to change what original deadline for converting transmission from digital to analog?

PROBLEM: Passage: The control of associated biodiversity is one of the great agricultural challenges that farmers face. On monoculture farms, the approach is generally to eradicate associated diversity using a suite of biologically destructive pesticides, mechanized tools and transgenic engineering techniques, then to rotate crops. Although some polyculture farmers use the same techniques, they also employ integrated pest management strategies as well as strategies that are more labor-intensive, but generally less dependent on capital, biotechnology and energy.

SOLUTION: What is one of the great polyculture challenges that farmers face?

PROBLEM: Passage: During the middle Ordovician Period (about 496-440 Ma), a change in plate motions set the stage for the first Paleozoic mountain-building event (Taconic orogeny) in North America. The once-quiet Appalachian passive margin changed to a very active plate boundary when a neighboring oceanic plate, the Iapetus, collided with and began sinking beneath the North American craton. With the birth of this new subduction zone, the early Appalachians were born. Along the continental margin, volcanoes grew, coincident with the initiation of subduction. Thrust faulting uplifted and warped older sedimentary rock laid down on the passive margin. As mountains rose, erosion began to wear them down. Streams carried rock debris down slope to be deposited in nearby lowlands. The Taconic Orogeny was just the first of a series of mountain building plate collisions that contributed to the formation of the Appalachians, culminating in the collision of North America and Africa (see Appalachian orogeny).

SOLUTION:
When did the Appalachian passive margin become quiet?