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 Q]: [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 A]: C

[EX Q]: [header] How to choose a protein supplement [title] Choose whey protein to build muscle. [step] If you're looking for muscle-building protein, whey protein is generally your best option. Whey protein can come in the form of powder or pills and is commonly used when people are trying to build muscle via things like weight training programs. <sep> (A) By doing this, you're gaining more body fat and growing more muscle at the same time. [substeps] Whey protein can be found in half of the packaged foods. (B) Whey protein is also a low-fat protein, rich in red blood cells from bacteria. Although whey protein does not impart healthy fats to the body, whey protein helps build muscle, which you can grow and burn through exercise. (C) [substeps] Look for a whey protein powder or supplement with a high biological value. This measures how well your body can absorb the protein. (D) Whey protein occurs as a food chain, hence the slogan, " protein is fat free ". [substeps] Whey protein is complex and varies from patient to patient.
[EX A]: C

[EX Q]: [header] How to remove dye from skin [title] Remove the dye as soon as possible. [step] Once you finish dying your hair, you need to act fast to remove any dye on your hands or on your hairline so it does not soak into your skin. Dye that is absorbed into your skin will be very difficult to remove and require a lot of scrubbing. <sep> (A) [substeps] Brush your hands lightly with warm water to remove dye from any skin that is not dyed. Take a damp paper towel and wipe the hair thoroughly to remove as much dye as possible. (B) [substeps] Avoid washing your hands after dyeing your hair. This could spread the dye to other areas of your body and cause lesions. (C) [title] Apply baking soda or toothpaste containing baking soda. [step] Baking soda is great at breaking down the dye's active ingredients and is only mildly abrasive. (D) Avoid excessive scrubbing and use gentle pressure when you are rinsing your hair so you can get out as much dye as possible. [substeps] Do not rub too hard or use a lot of force or you may damage the soft strands.
[EX A]:
C