Correct Option: B. Bright Explanation of the Correct Answer: Cotton plants require specific environmental conditions to produce high-quality bolls, which are the protective capsules that contain the cotton fibers. One of the most critical factors influencing the development of these bolls is sunlight.

1. Photosynthesis: Cotton plants, like all green plants, rely on photosynthesis to convert sunlight into energy. This process is essential for the growth and development of the plant, including the formation of bolls. Bright sunlight ensures that the plant can produce enough energy to support the development of bolls.
2. Boll Development: The bolls of cotton develop during the latter part of the growing season. Adequate sunlight during this period is crucial because it helps in the maturation of the bolls. Bright sunlight contributes to the overall health of the plant, leading to larger and more robust bolls.
3. Quality of Cotton: The quality of the cotton fibers is also influenced by the amount of sunlight the plant receives. Bolls that develop under bright sunlight tend to have better fiber quality, which is essential for the textile industry.

Why the Other Options are Incorrect:

• A. Big: While bright sunlight can contribute to the size of the bolls, the term "big" is too vague and does not directly address the role of sunlight in the development process. The focus should be on the quality and health of the bolls rather than just their size.
• C. Not mouldy: While bright sunlight can help reduce humidity and the risk of mold, this option does not directly relate to the primary function of sunlight in the development of bolls. The prevention of mold is more about environmental conditions than the direct impact of sunlight on boll production.
• D. Not open: This option suggests that the bolls should remain closed, which is not necessarily a requirement for healthy cotton production. In fact, bolls need to open at the right time to release the cotton fibers. The focus should be on the conditions that promote healthy growth rather than preventing the bolls from opening.

Summary:

• Bright sunlight is essential for the photosynthesis process in cotton plants, leading to energy production.
• Adequate sunlight during the boll development phase ensures the maturation and quality of the bolls.
• The other options (big, not mouldy, not open) do not accurately capture the critical role of sunlight in cotton production.
• Understanding the environmental needs of cotton plants is crucial for successful cultivation and harvesting.