Answer:
Option B.
Carbondioxide molecules.
Explanation:
Photorespiration lowers the efficiency of photosynthesis by removing carbondioxide molecules because photorespiration begins in Calvin circle as a result of Rubisco acting on oxygen instead carbondioxide and it's function is to first initiate and input carbondioxide in Calvin circle. Therefore instead of using Carbondioxide as the pathway , it uses oxygen. Carbondioxide is use for photosynthesis because it combine with water in the presence of light energy and chlorophyll to produce glucose and oxygen.