In a Harry Potter movie, there is a big pendulum in the Great Hall that
goes back and forth once every
18.9 s. What is the length of the
pendulum (if it obeys Physics
instead of magic)?

Depending on how the continental plates move it can cause a continental scale shift.

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.

Ibelieve the answer is either b or c, but i'm leaning more towards c.hope my answer has you : )