Given the task definition and input, reply with output. 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".

[header] How to find cat urine with a uv light [title] Buy a decent-sized uv or " fluorescent black " light. [step] Look for a long bulb (preferably longer than 12 inches) so you can cover more ground at once. Cheap bulbs with the housing included can be found at most hardware stores. <sep> (A) Check the batteries before you move onto the next phase. [title] Disinfect the area with an ultraviolet diode. (B) [title] Turn off the uv or fluorescent lighting as soon as the source isn't visible. [step] Uv and fluorescent lights make mistakes that you will regret. (C) Even if you do not have to use them to find a urine-soaked object, they will still give you a good, well-lit view. [substeps] Don't find any tunnels in your backyard, swamps, forests, runoff areas, or any other extensive environment that involves stagnant bodies of water. (D) Although pet stores sell the lights as well, they're usually smaller and more expensive. They can also be purchased at a reasonable cost online, depending on how much time you have to wait around living with the odor.
D