Which is the most formal and academic? Which is the least?

Look closely at the following five passages, each of which is from an opening of a published work, and decide a- which ones provide examples of academic argument? b- How would you describe each one, and what are its key features? c- Which is the most formal and academic? Which is the least?
1- During the Old Stone Age, between thirty-seven thousand and eleven thousand years ago, some of the most remarkable art ever conceived was etched or painted on the walls of caves in southern France and northern Spain. After a visit to Lascaux, in the Dordogne, which was discovered in 1940, Picasso reportedly said to his guide, “They’ve invented everything.” What those first artists invented was a language of signs for which there will never be a Rosetta stone; perspective, a technique that was not rediscovered until the Athenian Golden Age; and a bestiary of such vitality and finesse that, by the flicker of torchlight, the animals seem to surge from the walls, and move across them like figures in a magic-lantern show (in that sense, the artists invented animation). They also thought up the grease lamp—a lump of fat, with a plant wick, placed in a hollow stone—to light their workplace; scaffolds to reach high places; the principles of stenciling and Pointillism; powdered colors, brushes, and stumping cloths; and, more to the point of Picasso’s insight, the very concept of an image. A true artist reimagines that concept with every blank canvas—but not from a void.
—Judith Thurman, “First Impressions,” The New Yorker
2- I stepped over the curb and into the street to hitchhike. At the age of ten I’d put some pretty serious mileage on my thumb. And I knew how it was done. Hold your thumb up, not down by your hip as though you didn’t much give a damn whether you got a ride or not. Always hitch at a place where a driver could pull out of traffic and give you time to get in without risking somebody tailgating him. —Harry Crews, “On Hitchhiking,” Harper’s
3- Coral reef ecosystems are essential marine environments around the world. Host to thousands (and perhaps millions) of diverse organisms, they are also vital to the economic well-being of an estimated 0.5 billion people, or 8% of the world’s population who live on tropical coasts (Hoegh-Guldberg 1999). Income from tourism and fishing industries, for instance, is essential to the economic prosperity of many countries, and the various plant and animal species present in reef ecosystems are sources for different natural products and medicines. The degradation of coral reefs can therefore have a devastating impact on coastal populations, and it is estimated that between 50% and 70% of all reefs around the world are currently threatened (Hoegh-Guldberg). Anthropogenic influences are cited as the major cause of this degradation, including sewage, sedimentation, direct trampling of reefs, over-fishing of herbivorous fish, and even global warming (Umezawa et al. 2002; Jones et al. 2001; Smith et al. 2001). —Elizabeth Derse, “Identifying the Sources of Nitrogen to Hanalei Bay, Kauai, Utilizing the Nitrogen Isotope Signature of Macroalgae,” Stanford Undergraduate Research Journal
4- While there’s a good deal known about invertebrate neurobiology, these facts alone haven’t settled questions of their sentience. On the one hand, invertebrates lack a cortex, amygdala, as well as many of the other major brain structures routinely implicated in human emotion. And unsurprisingly, their nervous systems are quite minimalist compared to ours: we have roughly a hundred thousand bee brains worth of neurons in our heads. On the other hand, some invertebrates, including insects, do possess the rudiments of our stress response system. So the question is still on the table: do they experience emotion in a way that we would recognize, or just react to the world with a set of glorified reflexes? —Jason Castro, “Do Bees Have Feelings?” Scientific American
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