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". 

[Q]: [header] How to calculate a light year [title] Define the light year. [step] A light year is a measure of distance equal to how far light travels in one earth year. Because distances across the universe are so large, astronomers use light years. <sep> (A) However, they can also be determined by dividing by a distance. [substeps] Some light years are used year-round. (B) For light year 2014, the main determiner is the sun. In the light year, the world is filled with light bulbs. (C) Without light years, discussing the distance between two stars would require the use of large, unruly numbers. [substeps] Another measure of distance you may come across when learning astronomy is the parsec. (D) [substeps] There are two kinds of light years: day and night. The two types of light years are known as night and day.
[A]: C


[Q]: [header] How to make iced green tea [title] Boil 4 cups (950 milliliters) of water in a large pot. [step] If you would like to make a single serving, boil 1 cup (240 milliliters) of water in a kettle instead and pour it into a mug. [title] Take the pot off the stove, and add 4 to 6 tea bags into the water. <sep> (A) [step] Swish the tea bag or bag around in the water to help dissolve it, then you're ready to serve it. [title] Add 4 to 6 teabags to the pot. (B) [step] The more tea bags you use, the stronger your tea will become. If you would like to make a single serving, dip 1 tea bag into your mug. (C) [step] Make sure that the tea bags reach the proper amount of length to minimize the risk of scorching. [title] Turn the heat off and let the tea steep for 10 to 15 minutes. (D) [step] This will have the texture of a teaspoon of ginger. [title] Leave it to steep for about half an hour.
[A]: B


[Q]: [header] How to grow kumquat [title] Wrap kumquat seeds in a damp paper towel. [step] Soak the paper towel in tap water and wring it out. Spread the seeds across one half of the paper towel so they aren't touching and so they are evenly spaced from one another. <sep> (A) [substeps] Squeeze the excess water out of the seeds. Spread a layer of sterile vermiculite over both seeds and let them water for about 2 hours. (B) Fold the paper towel so the seeds are covered. [substeps] The more seeds you place in the bag, the more opportunities there are for them to germinate and start growing. (C) Let the seeds form a loose, pliable bundle. [substeps] Make sure the paper towel is non-transparent to you, otherwise you might damage the seedlings. (D) Keep them to 1 inch (2.5 cm) apart from each other. [substeps] You will add air to each seed to create air pockets in the germination bundle.
[A]:
B