How do temperature and water availability affect the efficiency of carbon fixation in C3 plants?

• A. High temperatures and low water availability increase efficiency by enhancing RuBisCO activity.
• B. High temperatures and low water availability reduce efficiency by increasing photorespiration.
• C. Low temperatures and high water availability reduce efficiency by decreasing RuBisCO activity.
• D. Temperature and water availability have no impact on carbon fixation efficiency.

Answer: (B)