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.
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Question: Passage: Paleoclimatologists measure the ratio of oxygen-18 and oxygen-16 in the shells and skeletons of marine organisms to determine what the climate was like millions of years ago (see oxygen isotope ratio cycle). Seawater molecules that contain the lighter isotope, oxygen-16, evaporate at a slightly faster rate than water molecules containing the 12% heavier oxygen-18; this disparity increases at lower temperatures. During periods of lower global temperatures, snow and rain from that evaporated water tends to be higher in oxygen-16, and the seawater left behind tends to be higher in oxygen-18. Marine organisms then incorporate more oxygen-18 into their skeletons and shells than they would in a warmer climate. Paleoclimatologists also directly measure this ratio in the water molecules of ice core samples that are up to several hundreds of thousands of years old.

Answer: Who measures oxygen-18 and oxygen-16 in skeletons of all organisms?


Question: Passage: Early Presbyterians were careful to distinguish between the "church," which referred the members, and the "meeting house," which was the building in which the church met. Until the late 19th century, very few Presbyterians ever referred to their buildings as "churches." Presbyterians believed that meeting-houses (now called churches) are buildings to support the worship of God. The decor in some instances was austere so as not to detract from worship. Early Presbyterian meeting-houses were extremely plain. No stained glass, no elaborate furnishings, and no images were to be found in the meeting-house. The pulpit, often raised so as only to be accessible by a staircase, was the centerpiece of the building.

Answer: What was the building where the images met called?


Question: Passage: There is no green pigment in green eyes; like the color of blue eyes, it is an optical illusion; its appearance is caused by the combination of an amber or light brown pigmentation of the stroma, given by a low or moderate concentration of melanin, with the blue tone imparted by the Rayleigh scattering of the reflected light. Green eyes are most common in Northern and Central Europe. They can also be found in Southern Europe, West Asia, Central Asia, and South Asia. In Iceland, 89% of women and 87% of men have either blue or green eye color. A study of Icelandic and Dutch adults found green eyes to be much more prevalent in women than in men. Among European Americans, green eyes are most common among those of recent Celtic and Germanic ancestry, about 16%.

Answer:
Where is the green pigment in eyes located?