What is the most likely consequence for a human of not spending at least 20 minutes a day with a portion of one's skin exposed to the sun?
digestion could slow down due to lack of warmth to speed up the reactions of enzymes.
bones could become brittle due to lack of vitamin d, which is needed for calcium absorption.
muscles could become weak due to lack of energy, which is needed to make the cells contract.
skin could lose its protective oily coating due to lack of adequate excretion from sweat glands.

Bones could become brittle due to lack of vitamin D, which is needed for calcium absorption.

Explanation:

The human who is not exposing to the sun for at least 20 minutes on daily basis may suffer from vitamin D deficiency as a result of which his bones will become brittle and fragile. Vitamin D is responsible for making our bones strong because it facilitates absorption of calcium which keeps our bones  healthy. Exposure to sunlight for at least 20 minutes in a day converts a steroid named 7 dehydrocholesterol in our body into vitamin D naturally. So, if a person will not expose to sunlight for at least 20 minutes in a day then he will suffer from vitamin D deficiency for sure.

picture a world where computers are building made-to-order personalized robotic arms and synthetic organs, drones are circulating above mars! due to the rapid growth of technology, the future has never been more unpredictable, and it presents a huge challenge in education: we are teaching students how to work in a future that we have never been unsure of. it is widely predicted that in eight years’ time, there will be more jobs in the fields of science, mathematics, technology and engineering than in any other discipline. and, as the technology continues to develop, it will soon become clear that addressing social problems will involve more innovative thinking, and analytical and technical knowledge than ever before. undeniably, there are no subjects that encourage innovative and creative thinking, deep thought, problem solving and independence more than the stem subjects. while it is widely commented on that there is a need to reimagine the ways stem subjects are taught in schools by embracing a more interactive and innovative approach to appeal to more students, it should come as no surprise that some of the most reputable educational organizations in the world are already implementing changes to embrace stem. harvard, for example, announced in 2014 that they were increasing their computer science faculty by over 50% and has since introduced computer science as a core subject for all freshmen. the urgency of supporting stem subjects at a young age is becoming more relevant than ever, as adopting a keen interest in the curricula needs to happen early. however, beyond the age issue is one of gender.

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a=c and then d= c because of the band so you get ac/dc and you add them together you get sound waves