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.

[Q]: 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.
[A]: Who measures oxygen-18 and oxygen-16 in skeletons of all organisms?


[Q]: Passage: Hard rock entered the 1990s as one of the dominant forms of commercial music. The multi-platinum releases of AC/DC's The Razors Edge (1990), Guns N' Roses' Use Your Illusion I and Use Your Illusion II (both in 1991), Ozzy Osbourne's No More Tears (1991), and Van Halen's For Unlawful Carnal Knowledge (1991) showcased this popularity. Additionally, The Black Crowes released their debut album, Shake Your Money Maker (1990), which contained a bluesy classic rock sound and sold five million copies. In 1992, Def Leppard followed up 1987's Hysteria with Adrenalize, which went multi-platinum, spawned four Top 40 singles and held the number one spot on the US album chart for five weeks.
[A]: In which decade did hard rock see a decline of dominance in commercial music?


[Q]: Passage: The southern portion of the Point Loma peninsula was set aside for military purposes as early as 1852. Over the next several decades the Army set up a series of coastal artillery batteries and named the area Fort Rosecrans. Significant U.S. Navy presence began in 1901 with the establishment of the Navy Coaling Station in Point Loma, and expanded greatly during the 1920s. By 1930, the city was host to Naval Base San Diego, Naval Training Center San Diego, San Diego Naval Hospital, Camp Matthews, and Camp Kearny (now Marine Corps Air Station Miramar). The city was also an early center for aviation: as early as World War I, San Diego was proclaiming itself "The Air Capital of the West". The city was home to important airplane developers and manufacturers like Ryan Airlines (later Ryan Aeronautical), founded in 1925, and Consolidated Aircraft (later Convair), founded in 1923. Charles A. Lindbergh's plane The Spirit of St. Louis was built in San Diego in 1927 by Ryan Airlines.
[A]:
What names was given to coastal artillery batteries erected shortly after 1825?