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 change strings on an electric guitar [title] Change your strings when they are rusty, gummy, or falling out of tune quickly. [step] If you're a serious guitar player you'll be changing your strings frequently, and some musicians change weekly. If your strings feel slow and sticky, or you have to re-tune frequently, you're due for new strings. <sep> (A) If you haven't restrung in 3-4 months, get new strings. [substeps] If you're about to play a big gig, change the strings that morning to prevent unexpected breaking. (B) [substeps] Always re-fret for better sounds, and get replaced often to prevent dropping strings or flying out of tune. [title] Replace the strings that fall out right after you've played. (C) [substeps] Before you begin switching your strings for an electric guitar, make sure you've checked the strings yourself and have signed a contract that says how long your strings will last. These clauses apply to any electric guitars you happen to buy. (D) Ask your guitar shop or guitar retailer which strings they'd recommend in determining the proper route. [substeps] If your strings are particularly dirty, you may want to replace them with new strings or fresh strings.
Solution:
A