Read the following passage and mark the letter A, B, C, or D to indicate the correct answer to each of the questions from 36 to 42.

Skin is a fairly good barrier that keeps out most of the external water. If our fingers did absorb a significant amount of water after staying in the pool or bath for several minutes, then our fingers would swell to round, plump shapes. Contrasting to a common misunderstanding, the wrinkling is actually caused by a reduction of fluid inside the fingertips. How can our fingertips experience reduced fluid internally when exposed to increased fluid externally? From a physical perspective, this effect seems to be a paradox. The answer is that the wrinkling of wet fingertips is an active biological response, rather than a passive physical one. Scientists have known for almost a hundred years that nerve damage in the hand can result in a person no longer being able to get wet-induced finger wrinkles. Finger wrinkling is therefore controlled by the nervous system. Nerve signals cause blood vessels in the fingertips to constrict, reducing the amount of fluid in the fingertips.

How could wrinkles ever help one survive? In the journal Brains, Behavior and Evolution, Mark Changizi and his associates at the 2AI Labs hinted at an answer to this question. They state, “We show that their morphology has the signature properties of drainage networks, enabling efficient removal of water from the gripped surface... Wet-induced wrinkles may, in fact, be substantially superior to 'rain treads' on shoes, which maintain a tread even when under compression and thus have a surface area of contact that is reduced. Wet-induced wrinkle treads, on the other hand, are pliable, and the act of pressing a fingertip down on a wet surface 'squeezes' the fluid out from under the finger through the channels, and upon completion of this single pulsatile flow the entire finger's skin contacts the surface.” A human with an improved grip can better handle tools and weapons in the rain, as well as retrieve food from rivers and streams.

Additional research carried out in 2013 by Kyriacos Kareklas and associates, as reported in Biology Letters, found that participants were able to transfer wet marbles and fishing weights between containers significantly faster if they had wet-induced finger wrinkles. While more research is needed to confirm these results, these studies suggest that the improved-grip hypothesis is a plausible explanation for wet-induced finger wrinkling.

(Adapted from: https://www.wtamu.edu/)

The word “pliable” in paragraph 2 means _______.