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". 

Example Input: [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.
Example Output: C

Example Input: [header] How to stay up late without electronics [title] Drink caffeine. [step] Caffeine blocks neurotransmitters in your brain that make you sleepy. When you start to feel drowsy, reach for a cup of coffee or a soda. <sep> (A) Remember that caffeine loses its effectiveness with overuse. Try to save it for when you really need it. (B) Your body will start shutting down caffeine when you're outside and keep you awake by doing what it is meant to do. It can help you stay awake long enough to go to bed. (C) Though caffeine will not give you energy right before sleep, it will trigger the natural sleep signal that draws us into the world right before it hits. An caffeine-rich beverage will wake you up more, making your sleep better. (D) Coffee is the source of human sleepiness so drinking coffee or another caffeinated beverage before bedtime is important. Even an extra pill is a key lubricant.
Example Output: A

Example Input: [header] How to teach kids to accept responsibility for their actions [title] Explain natural consequences. [step] As you go through your day with your child, make sure to talk about the ways that actions lead to certain results. This advice is not about punishment. <sep> (A) Rather, rather, this will teach your child responsibility not only for possible or potential consequences, but for how actions and consequences can help to boost child confidence and enthusiasm. [substeps] For example, you could say, " gravity causes our bodies to move along certain beat-ups. (B) Rather, it is about being a step ahead of them. This gives them guidance to learn to accept responsibility. (C) Rather, it's about discussing the ways that what a person does affects the eventual result. [substeps] For example, if your child brings home a good grade, you could say, " see, you got a good grade on this because you worked so hard. (D) It's about letting your child know that you are willing to work to minimize their negative behaviors. [substeps] Your child should understand that you will not punish them for behaviors that are not their fault unless told otherwise by their teacher.
Example Output:
C