<span>The lack of melanin tends to correlate with a lighter skin color. However, it also correlates with a higher susceptibility to receiving a sunburn. The more often a person burns, the more likely it is that a person will be susceptible to skin cancers later on in life.</span>
The answer is: the legumes will extinct, too.
It is known that plants cannot directly use atmospheric nitrogen. But, some legumes have a symbiotic relationship with bacteria that live in their root system. These bacteria are called Rhizobia and have the ability of nitrogen-fixation. In the root nodules, they use atmospheric nitrogen to convert it into ammonia, and later to ammonium, which can be used by plants. When legumes die, nitrogen from their remaining is released back to the soil where it is available to the other plants.
So, if <span>Rhizobia suddenly became extinct, the symbiotic relationship between will be interrupted. The legumes will not be able to use atmospheric nitrogen without the help of Rhizobia, and eventually, they will extinct, too.</span>
Diffusion<span> is a spontaneous movement of particles from an area of high concentration to an area of low concentration. ... </span>Osmosis<span> is the spontaneous net movement of water across a semipermeable membrane from a region of low solute concentration to a more concentrated solution, up a concentration gradient.
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Answer: A: Its fertile oases enabled farmers to grow enough food for themselves and for sale.
Explanation: The Arabia region is a region located within the Arabian desert. A desert is an area of extreme heat, often dry weather condition with barren lands that cannot support agriculture and food production. An oases on the other hand is a region of luscious, cultivate-able land within a desert.
Food is one of the most important basic needs of man and hardly can anyone survive without food for more than twenty days. Hence, the presence of oases within the otherwise dry environment of the Arabia region is a major protection against death from hunger.
Taking a closer look at other options, none of them guarantees food supply and income to the Arabia region unlike food production in oases. Hence, the fertile oases is really the most important factor that serves as protection in the region's history.
Correct option: A
