Answer:
Evolution occurs due to change in the characteristics of life.
Explanation:
The shared characteristics of life provide evidence for evolution. These shared characteristics are reproduction, homeostasis, heredity, growth, development and adaptation which occurs through evolution. The evolution mainly occurs due to changing environmental conditions. Some sea organisms such as whales evolve from land animals having four legs through the process of evolution. The environment of sea is responsible for the formation of gills and other body structure in order to survive in the water.
The answer is chemical energy