15. The model includes a wavy arrow to show light striking the thylakoids. Which
label for the wavy arrow would be MOST USEFUL for communicating the role of
light in photosynthesis?
a. Light is radiated from the chloroplast during the light-independent reactions.
b. Light energy is cycled within the thylakoid.
c. The chloroplast reflects the green wavelengths of light.
d. Light is the energy source for converting ADP to ATP, and NADP+ to NADPH.

This question is incomplete as it lacks the model, however, it can be answered based on general understanding of photosynthetic process. The answer is;

d. Light is the energy source for converting ADP to ATP, and NADP+ to NADPH.

Explanation:

Light dependent reaction, which is the first stage of photosynthesis, occurs specifically in the THYLAKOID of the CHLOROPLAST where the photons of light is absorbed by chlorophyll molecules (photosynthetic pigment). The light energy that hits the chlorophyll makes it excited, hence, providing the energy to produce ATP from ADP and NADPH from NADP+.

These products are pivotal in the next stage of photosynthesis (light independent stage). Hence, light plays a very crucial role in photosynthesis and the most useful way for communicating the role is by saying it provides the energy source for converting ADP to ATP, and NADP+ to NADPH.