Plant Conditions the plant was subjected to Result of potassium iodide test

Plant 1 Placed near a window, exposed to air and sunlight Stained dark, indicating the presence of starch
Plant 2 Placed near a window in the sun, but covered with a bell jar Stained light, indicating that very little starch was formed

Two potted plants were used in an experiment to study the amount of starch formed in leaves under different conditions. The table describes the conditions the plants were subjected to and the results of testing the leaves with potassium iodide to detect the presence of starch.

Which of these conclusions is BEST validated, based on the experimental data?
Responses
A Sunlight is essential for photosynthesis.Sunlight is essential for photosynthesis.
B Starch is not produced during photosynthesis.Starch is not produced during photosynthesis.
C Oxygen is not produced during photosynthesis.Oxygen is not produced during photosynthesis.
D Carbon dioxide is essential for photosynthesis.

The BEST validated conclusion, based on the experimental data, is:

A) Sunlight is essential for photosynthesis. The presence of starch in Plant 1, which was exposed to air and sunlight, and the lack of starch in Plant 2, which was covered with a bell jar, indicates that sunlight plays a crucial role in the formation of starch in leaves, which is a product of photosynthesis.