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 add potassium to an organic garden [title] Mix in muriate of potash or sulfate of potash. [step] Muriate of potash, or potassium chloride, and sulfate of potash, or potassium sulfate, are natural minerals. Muriate of potash tends to be cheaper, but the chlorine it contains can hurt the helpful microbes living in your garden's soil. <sep> (A) Gently mix these two together first, then add the zinc sulfate. [substeps] Zinc sulfate is readily available online, or in desalination solutions. (B) [substeps] You can substitute sodium thiamine (ipsin) or baking soda for sulfate because it is the most acidic fertilizer. Sodium thiamine is a common fertilizer in agricultural and organic gardens. (C) Sulfate of potash is safer, but it's a bit more expensive. [substeps] Check your product's label for specific instructions on how much to add per square foot or meter. (D) [substeps] There are many ways to add potassium to soil: you could use the most common method. You could sift the potassium into an empty feed colander and cool it before dropping it off.

Ex Output:
C


Ex Input:
[header] How to stop payment on a lost check [title] Check your account statement. [step] Before you initiate a stop payment on the check, you need to make sure it has not yet gone through. If your bank has already accepted the check, a stop payment won't do you any good. <sep> (A) [substeps] If you are unable to get a stop payment from your bank, you may wish to consider trying one of several other banks. [title] Avoid checking checks after they've expired. (B) Other circumstances may warrant a stop payment, such as : [substeps] If you purchased a loan, you might want to deduct the balance. A stop payment will result in interest, which you then pay off. (C) [substeps] Typically it's easier to check your recent transactions on your online account, or on your banking mobile app if you have one. Make sure the check has not cleared, and also check your pending transactions to make sure it hasn't been presented yet. (D) If you believe it was lost, you can call the bank directly. [title] Confirm that you can't keep the check.

Ex Output:
C


Ex Input:
[header] How to study vocabulary words [title] Choose paper or electronic flash cards. [step] Paper flash cards are easy to carry around, and writing by hand may help you memorize the words more than typing. On the other hand, you can't lose a phone app or online tool. <sep> (A) If you've got a lot of time on your hands at work, buying flash cards can help you study faster and learn more vocabulary words. [substeps] If you are going through a difficult time, it is often useful to bring your wallet so you can take care of your wallet. (B) If you've never used a flash card before, an online flash card can take you far from what you need to remember. [substeps] Tablets, smartphones, and laptops can also be useful. (C) Some flash card software even lets you speak the words aloud, then writes the cards for you. [substeps] If using paper cards, try to find something small that you can carry in your pocket. (D) Another option is to stick with the electronic flash cards, which are durable and easy to carry around. Turn them into fancy writing cards, or use construction paper.

Ex Output:

C