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". 

Ex Input:
[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.

Ex Output:
B


Ex Input:
[header] How to polish rocks [title] Choose the right rock. [step] You can polish any stone you wish, but there are certain characteristics of a stone that will make it easier to polish. If you want an easy stone to polish, pick a somewhat softer stone like onyx, limestone or calcite. <sep> (A) [substeps] You can polish diamond, granite or ceramic stones by cutting thin pipe holes or inserting dry mortar into one side of each hole. Look for a stone that resembles a diamond, but not necessarily a diamond. (B) Otherwise, a smoother, more pumice-like stone will be more difficult to polish. [substeps] Emeralds and equilateral manganese are both excellent mineral polishes. (C) Stones that are very hard will take a much longer time to polish. However, though hard rocks take a long time to sand, they yield more shine than softer rocks. (D) Softer rocks will actually work more well, and might look better to polish very old stones, but brighter stones tend to chip quicker. [substeps] Rubies, sapphires, and emerald are good options.

Ex Output:
C


Ex Input:
[header] How to keep your home free of rodents [title] Clean the crawl space. [step] If you've got rodents, you'll see the insulation hanging down (they like to nest in it) and droppings on the vapor barrier. If it is bad, get rid of both. <sep> (A) The spiders begin to return if they see this. [substeps] Get rid of rats, too, so they won't get into your home with you. (B) Once the area is clean, you can see what needs to be done. Rodents can carry some nasty diseases (hantavirus for one, but it is rare) so you may want to wear high-quality respiratory protection. (C) Wild rodents are clever, and will try to crawl through any run-off that they can find to escape. [substeps] Look for flashing green, and can scent a crowded crawl space. (D) Just try different rooms and find ways to stop them from making their nest. [substeps] The crawl space should be deep enough to store mice in, but not so deep that rats cann't crawl.

Ex Output:

B