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 change the string on a lawn trimmer [title] Prepare the line. [step] The length and width of line you need varies based on your trimmer. If you purchase the wrong width of line, the trimmer will not work correctly, so don't waste your money by simply guessing at the hardware store. <sep> (A) If you are not sure what size line your trimmer uses, check online-the manufacturer's website often has instructions, and if not the customer service department should be able to help you. The length to which the line should be cut also varies, from around 10' to 25'. (B) [substeps] Use a marker to mark the line so you can differentiate it from other lines so you know what kind of tool to use to cut the line. If the length is the same, the string you use to cut the line may not work properly. (C) Most trimmers come with a flexible line, rather than a heavy line, so take your time to figure out the best way to customize it. [substeps] Make sure your line length is proportional to the attachment of the trimmer, so the line width will not change when you trim off a grass shoot. (D) [title] Attach the line to your trimmer with a detachable clip. [step] On both trimmers, find a start on the length portion of the trimmer and use the detachable clip to attach the entire line to it.
A