Identifying the target population or target audience occurs during which step of the engineering design loop a identified the need b research the problem or c develop possible solutions

C I believe is the correct answer. Developing possible solutions would be easier than spending hours researching or identifying the need.

The answer is water molecules are split.cellular respiration and photosynthesis are complement  reactions to each other. these are reverse reactions. in cellular respiration glucose and oxygen yield water and carbon dioxide. so, when respiration begins,  glucose molecules are split. in the opposite reaction - in photosynthesis, carbon dioxide and water yield glucose and oxygen. thus,  when respiration begins, water molecules are split.

That big glowy thing in the sky is called the sun