People die because of the sin in the world, when Adam and Eve were created they were not supposed to get sick or die they were allowed to do anything in the garden God put them in except take the fruit from this one tree but they disobeyed God and ate the fruit so God punished them and made them work very hard for a living and told them that they will soon die and all of their children will too (Which we are there children). So that is why people die based on my religious reasons.
The answer is a)growth and development is a gradual
It because it heavy rember there nothing that holds the fat
