I believe the answer is A) Foot
Soil creation is a result of carrying out successions. Succession is the process in which land that is inhabitable by organisms is reclaimed and made fertile. This is done using pioneer species, which do not require soil to grow. After a while, these species are removed and a secondary succession is carried out. After this process, soil is created and the land becomes fertile.
In the case of liquid droplets, including water, surface tension is the factor, which is accountable for their shapes and configuration. Though can easily be malformed, the droplets of water seem to be pulled into a spherical shape due to the cohesive forces of the surface layer.
In the non-existence of other forces, involving gravity, the drops of almost all the liquids would be almost spherical.
To calculate the population density, you will divide the population by the size of the area. Hope I helped!
