The "photo-" part of the word photosynthesis refers to the whereas "-synthesis" refers to
a. light reactions that occur in the thylakoids : carbon fixation
b. calvin cycle : carbon fixation
c. calvin cycle : the reactions in the stroma
d. reactions in the stomata : the reactions in the thylakoids

The correct answer is a. light reactions that occur in the thylakoids : carbon fixation

Explanation:

In the term, photosynthesis photo indicates light and synthesis indicates the formation of food that is glucose by carbon fixation. So photosynthesis is the process in which plants use photons energy(light energy) to make their food.

To absorb the sunlight plants have a green pigment called chlorophyll that is present in the membrane of the thylakoid. So the incident light is absorbed by the chlorophyll and use its energy in the fixation of carbon dioxide to form glucose.

Thylakoid is surrounded by the fluid called stroma which has important enzymes that help in the process of carbon fixation during photosynthesis.

Therefore the correct answer is a. light reactions that occur in the thylakoids: carbon fixation.