Answer the following question given this paragraph: 

13 Photosynthesis 6 CO2 + 6 H2 O → C6 H12 O6 + 6 O2 • One of most important reactions in history of life: • source of atmospheric O2 • ultimately led to aerobic respiration and eukaryotes • Responsible for bulk of glucose production • Early experiments showed that mass of plant must be derived from substances in the air, not the soil • Experiments with isotopes showed that liberated oxygen comes from water • Experiments also showed that light is essential but that some reactions (e. , reduction of CO2 ) continue in the dark • Plants do two big, important things during photosynthesis: gain energy (absorb light) and build sugar (glucose). • Photosynthesis can be divided into two series of chemical reactions: the light (lightdependent) reactions and the dark (light-independent) reactions. In light reactions, light is absorbed; in dark reactions, sugar is built. • Occurs when plants, algae, and autotrophic bacteria absorb light energy and build glucose.


Q: What is the process by which plants gain energy and produce sugar?

 Choices:

- glycolysis

- respiration

- chemosynthesis

- photosynthesis

A:
photosynthesis
