A. Although crying is universal to almost all human beings, this natural bodily function has received little attention from researchers, who know much more about how and in what ways we cry than why we cry. As a bodily process, crying involves the secretion of a salty, protein-rich fluid that is produced by both the tarsal and the lachrymal glands, located on the underside of our eyelids. Together these glands are responsible for the tear production process.

B. The tarsal glands constantly produce oily, nutrient-rich basal tears—up to 10 ounces a day—in order to lubricate and nourish our eyes during both our waking and sleeping hours. In contrast, reflex tears are produced by the lachrymal glands, primarily in order to flush out foreign particles in the eyes and to protect our eyes from irritants such as chemicals, allergens, or even vapours from raw onions. The glands that produce reflex tears are also responsible for emotional tears.

C. Of the three types of tears that humans produce, emotional tears puzzle scientists the most. Human beings seem to be the only animals that shed emotional tears. What mystifies experts is the question of whether or not there is a biological benefit to these tears and, if there isn't, why they were not weeded out in the process of evolution. As infants, it is advantageous for us to cry so that we will get fed or receive care if we are in pain. Why, though, do we continue to cry as adults? Some researchers argue that crying might be a sort of vestigial behaviour, persisting after infancy because it still serves to manipulate others into giving us what we want. Yet this theory does not account for why we cry in situations where we apparently have nothing to gain by doing so, such as at sad movies.

D. It is possible that emotional tears are a communication method of last resort—the only thing left when words fail us. Whether or not this is the case, emotional tears are associated with certain health advantages. Studies have shown that those who weep from time to time seem to have lower rates of ulcers, migraine headaches, heart problems, and other diseases. Perhaps, then, tears are the body's way of ridding itself of emotional toxins. Whether or not this is true, it seems reason enough to let go once in a while and have a "good cry."

E. Not given in any of the above paragraphs.