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 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 buy a blackhead remover [title] Learn your options. [step] You should not squeeze or pick at blackhead, as this can lead to infection or scarring. However, you can remove pesky or unsightly blackheads with several different types of products that may not necessarily irritate your skin or require treating it with chemicals. <sep> (A) Learning your different options can help you identify the best product for your specific blackhead removal needs. Products that can remove blackheads include : [substeps] Extractor tools pore strips clay masks topical creams [title] Identify the best remover for your skin type. (B) For example, cleansing a burnt face can peel pores, like blackheads, and subtly remove blackheads. Deep pore pimples, which are a common factor for blackheads, are not tended to dry out. (C) [substeps] Avocado, keratin, and brewer's yeast all work well in reducing the inflammation and scarring of blackheads. [title] Pick a chemical neutralizer for stubborn blackheads. (D) Some of the well known brands that are known for their blackheads include tootane, steam, huawba, and celandine. As noted above, these products are more environmentally friendly than other skincare products, especially for those kids.

Ex Output:
A


Ex Input:
[header] How to calculate typing speed [title] Choose a text. [step] You need to type from a text to calculate your speed. Try not to pick the simplest text you can find. <sep> (A) You can use quotes or a passage from a book or news article. Stick with prose rather than poetry or song lyrics. (B) Texts always have faster times and simpler structures. [title] Cross out the word " typing speed ". (C) Still, look at speed in the text you are typing and get an overall idea of how you can calculate it. [substeps] For example, say you're typing headstock text into a text box with the symbol for typing speed. (D) This means choosing the quickest and most concise option for typing. [substeps] To calculate type speed for any length of a sentence, add.

Ex Output:

A