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". 

Example Input: [header] How to clean a plastic water tank [title] Open the outlet valve or tap. [step] The first step to cleaning your tank is to empty all of the water from it. To do so, open the outlet valve or tap at the bottom of your tank and let all of the water flow out. <sep> (A) [substeps] You may find that there's extra water in your tank that you need to empty. Read the instructions carefully to see if your water is full enough to remove. (B) You will have to remove several pieces of tank flooring to access one. For the best results, take the steps above. (C) Then, use a bucket to wipe the water down away from the water line, then gently empty the tank contents into the toilet. [substeps] You should also clean the water tank once every few months to keep it clean. (D) [substeps] Connect a hose to the open valve in order to direct the water to a location where it will not cause any localized flooding or erosion. Permanent water tanks have a washout valve that is located at the base of the tank.
Example Output: D

Example Input: [header] How to restore a boat [title] Make a plan. [step] Plan your work by breaking everything down into sections, like chapters in a book. Chapter one is planning. <sep> (A) This is where your business development can start. Analyze the navigation board, take all the necessary materials and then create your grand vision. (B) This step is not yet complete, so you need to prioritize moving toward part 1 of the project. This will help you tackle all your major projects faster, so that you can review your own work by taking each section and remembering to include the steps in that section over time. (C) The next phase might be stripping the boat in preparation for the work. [title] Prepare a work site, gather tools and supplies, carve out a dedicated time on a regular basis with your schedule, consult experts in the field, and also outsource certain components as needed to certain experts. (D) Plan your time on your own to avoid confusion and frustration with each chapter. Be sure that you aren't scrambling for ideas as you go forward so that you don't get overwhelmed by too many ideas.
Example Output: C

Example Input: [header] How to maintain indoor fountains [title] Keep your fountain pump submerged in water at all times. [step] This will help circulate the water in your fountain and keep it filtered, in addition to minimizing the growth of algae. Your fountain pump may also become dry and burn out if it is not submerged in water consistently. <sep> (A) [substeps] Examine the water level around your fountain pump on a daily basis. This will allow you to become familiar with how often you need to add water to the fountain. (B) Some fountain pump models come with a valve that can be adjusted simply with the thumb button and the smallest screw. [substeps] It's the nucleus found on both front and rear of your fountain pump near the control panel. (C) [substeps] If your fountain pump is under water and you do not regularly run it under water, it is likely to develop algae. [title] Float your fountain when it is not running. (D) Make sure there aren't any cracks or other leaks in your fountain pump. [title] Keep your fountain pump in a central location that's protected from heat and humidity.
Example Output:
A