instruction:
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.
question:
Passage: External evidence is evidence of each physical witness, its date, source, and relationship to other known witnesses. Critics will often prefer the readings supported by the oldest witnesses. Since errors tend to accumulate, older manuscripts should have fewer errors. Readings supported by a majority of witnesses are also usually preferred, since these are less likely to reflect accidents or individual biases. For the same reasons, the most geographically diverse witnesses are preferred. Some manuscripts show evidence that particular care was taken in their composition, for example, by including alternative readings in their margins, demonstrating that more than one prior copy (exemplar) was consulted in producing the current one. Other factors being equal, these are the best witnesses. The role of the textual critic is necessary when these basic criteria are in conflict. For instance, there will typically be fewer early copies, and a larger number of later copies. The textual critic will attempt to balance these criteria, to determine the original text.
answer:
External evidence is evidence of each physical witness, its date, source, relationship to other known witnesses, and what else?

question:
Passage: New Zealand has a strong hunting culture. The islands making up New Zealand originally had no land mammals apart from bats. However, once Europeans arrived, game animals were introduced by acclimatisation societies to provide New Zealanders with sport and a hunting resource. Deer, pigs, goats, rabbits, hare, tahr and chamois all adapted well to the New Zealand terrain, and with no natural predators, their population exploded. Government agencies view the animals as pests due to their effects on the natural environment and on agricultural production, but hunters view them as a resource.
answer:
What mammal was the only one that existed originally in Europe?

question:
Passage: Predatory animals often use their usual methods of attacking prey to inflict or to threaten grievous injury to their own predators. The electric eel uses the same electric current to kill prey and to defend itself against animals (anacondas, caimans, egrets, jaguars, mountain lions, giant otters, humans, dogs, and cats) that ordinarily prey upon fish similar to an electric eel in size; the electric eel thus remains an apex predator in a predator-rich environment. A predator small enough to be prey for others, the domestic cat uses its formidable teeth and claws as weapons against animals that might confuse a cat with easier prey. Many non-predatory prey animals, such as a zebra, can give a strong kick that can maim or kill, while others charge with tusks or horns.
answer:
What method is used by giant otters to prevent their prey from attacking them?