Answer:
um you don't have the answer to choose from so I looked up on the web and its says ( migrants are more prepared to take on low-paid low-skilled jobs - helps to reduce any labor shortages) I'm pretty sure this didn't help but I hope it did
Descending tracts are the pathways by which motor
signals are pass through from the brain to lower motor neurones. Thus, all
the neurones within the descending motor system are classed as upper motor
neurones. The lower motor neurones then directly innervate muscles to produce
movement. Their cell bodies are found in the cerebral cortex or the brain stem,
with their axons remaining within the CNS.
This is because of the populations.
Less water would make a large population dehydrate.
The other is a result of ones radiation or sun exposure
