If a photosynthetic organism is illuminated in a closed, sealed environment, it is observed that the CO2CO2 and O2O2 levels in the surrounding atmosphere reach a constant ratio. Part A Suggest an explanation. Match the words in the left column to the appropriate blanks in the sentences on the right.

Which of the following statements best distinguishes a hypothesis from a theory? a. theories are hypotheses that have been proved. b.hypotheses are guesses; theories are correct answers c. hypotheses usually are relatively narrow in scope; theories have broad explanatory power. d. theories are proved to be true; hypotheses are often contradicted by experimental results.