The answer is c because the other are soft
<span>Neils Bohr </span>developed a model of the atom (Bohr model) to explain how the structure of the atom changes when it undergoes energy changes. His major idea was that energy of the atom was quantized (this means that the atom could only have very specific amounts of energy) and the amount of energy in the atom was related to the electrons possession in the atom. In the Bohr model, electrons travel in orbits around the nucleus. The further the electron from the nucleus the more energy it has. Bohr used Planck's quantum concept of E=hv.
It flows through the consumers (first level second level so forth). However, at each level, it loses 90 percent of the energy as heat. So at each level, each consumer will only get 10 percent of the energy.
Water or other molecules move down their concentration gradient without any energy.........
difference - simple diffusion uses help of transporting protein in the membrane whereas osmosis uses no help.