instruction:
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". 
question:
[header] How to install custom firmware [title] Record the router's model and version number. [step] These numbers are usually located near the manufacturer's logo, underneath or in back of the router. Write down the model and version information for future use. <sep> (A) [substeps] If you are using windows xp (default operating system), the model number can be found in the start menu under " system settings. " skip all the discussion menus, and then go to system preferences. (B) [title] Obtain the router's ip address and default gateway for your computer system. [substeps] Determine the ip address and default gateway for a pc. (C) [substeps] " w " with the green background is the serial number for the model. " p " with the red background means " unhappy operating system. (D) [substeps] It is easy to determine what operating system is running on your router if you don't know the model. Copy the model from the registry to convert it to your operating system.
answer:
B


question:
[header] How to avoid common glass tile installation mistakes [title] Ensure color consistency behind glass tile. [substeps] Since glass can be the sole material in an installation, it is essential to choose a bonding mortar that meets its unique demands. In most cases, the color of the thin-set mortar was not an issue when installing opaque ceramic tile. <sep> (A) But with clear and translucent glass, the mortar appears through the tile: if the color varies in the mortar, it will in the glass tile too. To eliminate variations across a glass tile installation, choose a glass tile mortar with a bright white shade that is controlled to a consistent standard color. (B) [title] Find a masonry solution solution as described in this article. [step] Masonry solutions used to be sold in commercial suppliers were expensive and less durable than those containing glazed portions. (C) [title] Check your online repair and installation guide for common glass tile installation recommendations. [substeps] If you cannot find the recommended measurements, consult the manufacturer's website or consult the recommended supplies list. (D) Spray glass tile debris on the glass tile before continuing. Rinse glass tile debris with water and wipe the water away.
answer:
A


question:
[header] How to improve written communication [title] Take your audience into account. [step] It's important to choose the right words depending on your audience. For example, you should use formal language when sending an email to your boss or drafting a cover letter for a job application. <sep> (A) Adopting more formal language can help improve communication skills. [substeps] For example, you can even use the word " thank you " if the person you're writing for is a supervisor in your company. (B) Save your informal language, such as beginning an email with " hey, " for close friends and family. [title] Explain unfamiliar concepts, terms, and data when necessary. (C) Getting your audience's attention is very important, so your writing should reflect that. However, you can also try using the tongue twister. (D) But, when spelling words out loud, you should have written them out in vivid and concise terms. Even with proper grammar, try to be respectful of the audience.
answer:

B