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
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Q: [header] How to start a taxi company [title] Investigate whether there's a need for a taxi company in your area. [step] In smaller towns, the demand for taxis usually isn't so high, so considering a different location to start a taxi company might be a wise choice. [title] Determine your niche. <sep> (A) [step] What is the ideal type of taxi company or whether the need is a strong job market. However, there's also a reason you could (and probably should) start a taxi company for a fee. (B) [step] Taxi companies and vegans have a pressing concern in their treatment for foreigners in countries. Decide what you wish to be used for based on your niche and behaviors when applying for a taxi company. (C) [step] Though most taxi companies cater to all types of customers, there are those that cater to high-end clientele such as politicians, diplomats, and executives. Other taxi companies offer adapted vehicles for the physically impaired, while yet others provide green taxis for environmentally-conscious customers. (D) [step] To start a taxi company, you will first need to determine your own niche, and how much money you're willing to spend on the service. This is where you'll be able to make the hiring process go more smoothly.

A: C
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Q: [header] How to do brain training [title] Learn something new. [step] Keep your brain stimulated and active by picking up a new habit. Practicing something new forms new neural pathways in your brain. <sep> (A) Repeating the same action over and over strengthens these newly formed brain pathways. The more you use your brain, the better it will work. (B) Mindfulness is a great introduction to new habits. Don't just rush to start learning, you can ultimately become a better learner by learning something new every day. (C) The more you learn something new the more ideas you will have. For example, learning the basics of a musical instrument builds a new passion for the instrument. (D) It's a new skill that both people who do brain training and their professions get used to. [substeps] Get out of the habit of following a strict routine, or instead try something new.

A:
A
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