Which of the following best describes controlled atmosphere storage?

Controlled atmosphere storage is a preservation technique that significantly extends the shelf life and maintains the quality of specialty crops during storage. This method involves regulating the composition of gases in the storage environment, notably oxygen and carbon dioxide levels, to slow down the respiration rates of the stored crops.

By creating a specific atmosphere that is optimal for the specific crop being stored, this technique helps to reduce spoilage and maintain freshness, color, texture, and taste. This is particularly important for fruits and vegetables that are sensitive to ethylene gas and other factors that can accelerate ripening and decay.

The other choices relate to different agricultural practices. For instance, marketing specialty crops focuses on selling and distributing the products, which is distinctly different from the storage methods described in controlled atmosphere storage. Irrigation methods are related to the application of water to crops, which does not pertain to storage techniques. Genetic modification involves altering the DNA of plants to enhance certain traits, which is also a separate concept from storage preservation methods. Thus, the focus of controlled atmosphere storage squarely fits within the realm of preserving crop quality during storage.