<span>The bottleneck effect is the cause of the sudden shift in the genetic information of the population. Due to the landslide, suddenly high number of the members of the main population died, and this caused genetic drift for reducing the variation in the existing generation, which is now widely different from the original one.</span><span />
The order of blood pressure in blood vessels would be letter "D. veins < capillaries < arteries". The arteries carry the blood towards the veins and has relatively thicker walls because of high pressure. The vein carry blood from capillaries back to the heart.
It is difficult to calculate the Earth's carrying capacity because there are lots of resources that we can use and their is so much land on the earth that hasn't been used, but at the same time some resources are running low, and some resources we have a lot of, like food, so that it is why it is difficult to calculate