The right answer is the chloroplast.
Autotrophic species must stock up on food in order to have energy at all times.
Plants, for example, through their chloroplasts make sugar with the energy of sunlight and from soil water and carbon dioxide from the air. This sugar synthesis using light is photosynthesis.
Answer: For the scientist to have alternative hypothesis considered, it is imperative he takes certain steps, this steps will ascertain the scientific claims already made about the evolution of species.
Therefore,the scientist will simply test the alternative hypotheses inorder to know that they are incorrect.
This testing of hypotheses to ascertain their incorrectness is very useful in the study of fossils.
There are many answers to your question but one way is the evaporation cycle.