This task is about reading the given passage and construct a question about the information present in the passage. Construct a question in such a way that (i) it is unambiguous, (ii) it is answerable from the passage, (iii) its answer is unique (iv) its answer is a continuous text span from the paragraph. Avoid creating questions that (i) can be answered correctly without actually understanding the paragraph and (ii) uses same words or phrases given in the passage.

[EX Q]: The state is also a host to a large population of birds which include endemic species and migratory species: greater roadrunner Geococcyx californianus, cactus wren Campylorhynchus brunneicapillus, Mexican jay Aphelocoma ultramarina, Steller's jay Cyanocitta stelleri, acorn woodpecker Melanerpes formicivorus, canyon towhee Pipilo fuscus, mourning dove Zenaida macroura, broad-billed hummingbird Cynanthus latirostris, Montezuma quail Cyrtonyx montezumae, mountain trogon Trogon mexicanus, turkey vulture Cathartes aura, and golden eagle Aquila chrysaetos. Trogon mexicanus is an endemic species found in the mountains in Mexico; it is considered an endangered species[citation needed] and has symbolic significance to Mexicans.
[EX A]: The state hosts populations of birds of both endemic species and what?

[EX Q]: Paper is often characterized by weight. In the United States, the weight assigned to a paper is the weight of a ream, 500 sheets, of varying "basic sizes", before the paper is cut into the size it is sold to end customers. For example, a ream of 20 lb, 8.5 in × 11 in (216 mm × 279 mm) paper weighs 5 pounds, because it has been cut from a larger sheet into four pieces. In the United States, printing paper is generally 20 lb, 24 lb, or 32 lb at most. Cover stock is generally 68 lb, and 110 lb or more is considered card stock.
[EX A]: What characteristic is paper usually classified by?

[EX Q]: Studies by Nathaniel Kleitman in 1938 and by Derk-Jan Dijk and Charles Czeisler in the 1990s put human subjects on enforced 28-hour sleep–wake cycles, in constant dim light and with other time cues suppressed, for over a month. Because normal people cannot entrain to a 28-hour day in dim light if at all,[citation needed] this is referred to as a forced desynchrony protocol. Sleep and wake episodes are uncoupled from the endogenous circadian period of about 24.18 hours and researchers are allowed to assess the effects of circadian phase on aspects of sleep and wakefulness including sleep latency and other functions.[page needed]
[EX A]:
What time cycle did studies in 1938 and 1990s use on humans?