Detailed Instructions: 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".
Problem:[header] How to clean a fish bowl [title] Figure out how much water your bowl holds. [step] In order to determine how much clean water you'll need to prepare, you first need to gently pour the bowl's current water and the fish into a clean, soap-free bucket or container. Then, mark the water level on the outside of the bucket. <sep> (A) This will give you specific guidelines about how much water each container should hold. Fill a bucket or container with warm, soapy water and set it underneath your bowl. (B) [substeps] Only use water that is sterilized. The amount of clean water your bucket holds will vary with the amount of fish you intend to clean. (C) [title] Figure out how much new water you'll need. [step] When you clean your fish bowl, you'll need to replace 40-50% of the total volume of water that it holds. (D) Repeat this process for each gallon or liter of water that you use. [substeps] Be sure to record this number for easy reference.
Solution:
C