In this task, you are given a context and four options. Each option is a suggested ending for the context. You should read the context and pick the best ending for the context. Please answer with "A", "B", "C", and "D".
Q: [header] How to keep your plant nursery clean [title] Give your nursery a thorough cleaning before winter. [step] Keeping the nursery or greenhouse clean works well as a defense against plant diseases and insect infestations. Begin with a thorough cleaning of the entire nursery in the fall. <sep> (A) In addition to the plant nursery, try also walking through your entire flower garden once a week. This will remove especially powdery material that could get into circulation, and will reduce the appearance of grey or powdery mold. (B) Clean it all out, then put it back in order before winter rolls up. [substeps] Remove the shelves, carpet, and other materials from the areas where the plants could be moved. (C) If the nursery are not ahead of schedule and using chlorinated water, clean the interior and exterior of all areas with disinfectant. Then discard any plants after removing them; otherwise, bacteria may grow. (D) The growing season is over at that time, the weather is beginning to cool and insects are looking for a warm home for the winter. [substeps] Disease organisms also survive the winter in greenhouses, only to attack with a vengeance when the temperatures warm back up.
A:
D