Proteins are involved in light reaction of the photosynthesis are present in the five complexes: thylakoid membrane, photosystems, cytochrome bf complex, thylakoid lumen and ATP synthase. Photosystem I and II in plants are associated with the generation of ATP and NADPH molecules respectively.
If a protein changes their shape in response to temperature it will directly affect the electron transfer chain (will not be transferred) due to which H+ ions transport will also be affected which are involved in the production of ATP molecules.
Thus, option C- a decrease in ATP production is the correct answer.
