Identify a coordinate system you could use to describe the motion of a girl swimming across a rectangular pool

If we imagine the rectangular pool to have a length L and a breadth b, the attached figure shows one of the several possible coordinate systems that can be used to locate the position of the girl at any point of time, thus enabling us to describe her motion.

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.