The correct answer is A, parathyroid gland.
The parathyroid hormone is secreted by the parathyroid gland which <span>inhibits osteoblasts, stimulates osteoclasts,</span> reduces the calcium output by the kidneys and promotes absorption of the calcium by the small intestines. Calcitonin, secreted by the thyroid gland, also works to a similar effect.
84.798 is the mass number
The first known single-celled organisms appeared on Earth about 3.5 billion years ago, roughly a billion years after Earth formed. More complex forms of life took longer to evolve, with the first multicellular animals not appearing until about 600 million years ago.
Answer:
Although humans can sometimes influence natural disasters (for example when poor levee design results in a flood), other disasters that are directly generated by humans, such as oil and toxic material spills, pollution, massive automobile or train wrecks, airplane crashes, and human induced explosions, are considered.
