Answer:
The correct answer is: geography and UV radiation.
Explanation:
Skin variation occurred thanks to evolution, and was driven as a consequence of the geographical location of different populations of humans.
The humans that lived in hot and sunny places, closer to the equator, where much more exposed to the sun's ultraviolet radiation. In order to survive the amount of UV lights that they were exposed to, new humans in those regions were being born with a darker skin tone, which was rich in melanin (a brown pigment that protects us from the sun radiation).
Contrary to these humans that lived in the tropical areas, the humans that populated the areas that were closer to the poles, developed much lighter skin as a result of lower amounts of melanin in their skin. Since sun exposure in the poles is very limited, humans needed to receive as much as they could for the production of Vitamin D, and thus, their skins got lighter and less protected.
Answer: D. Galaxies show a red shift, indicating they are moving away from each other.
Explanation:
Galaxies seem to show a red shift which indicates that the galaxies are moving away from each other. This provides evidence for the Big Bang theory because the theory posits galaxies will keep moving away from each other.
This is because when an explosion happens, matter moves away from the point where the explosion happened. If the Big Bang happened therefore, galaxies will move away from the source which is why galaxies are moving away from each other.
Answer:
Intrusive rocks are coarse-grained in texture and crystallise slowly from magma deep in the earth's crust. Extrusive rocks are fine-grained in texture and crystallise quickly from lava on or near the earth's surface. The mineralogy determines the type of rock.
Answer: No. You would not withdraw CSF if the needle is in the epidural space.
Explanation: There are 3 spaces that cover the spinal cord, which are epidural, subdural and subarachnoid spaces. The epidural space is the outer most space while the subarachnoid space is the inner most space. CSF flows from the brain where it is produced to the spinal cord. In the spinal cord it flows only in the subarachnoid space. Thus you would not be able to withdraw CSF if the needle is in the epidural space.