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 study the phenomenon of light as a nonequilbirum state of matter [title] Understand how thermodynamic systems are categorized. [step] Thermodynamic systems in nature are divided into two types. One is systems that are at equilibrium state with the environment and the other is systems that are in a state of nonequilibrium with the surroundings. <sep> (A) On earth, nature has a preference for systems that are at an equilibrium state with the surrounding. This is so due to the principle of minimum energy that every object in the universe aspires to have. (B) For example, gas rising in temperature throughout the day can be divided into microorganisms in the environment. [substeps] For example, gas rising in temperature in the atmosphere can be divided into molecules in the environment. (C) [substeps] Equilibrium is fundamental in thermodynamics. Other systems include stars, planets, and oceans. (D) [title] Learn about the term " rock hydrodynamics ". [step] Rock hydrodynamics refers to the transfer of water to the earth's surface.
[A]: A


[Q]: [header] How to deal with an identity crisis in college [title] Access campus counseling services. [step] Identity issues are quite common for college students, of whom about 8% have identity problems. The psychological effects of these issues can lead to things like depression, anger, loneliness, and hopelessness. <sep> (A) Cultivate a plan to handle these problems. Attend campus counseling services regularly with the parents of your child or teen in particular. (B) You can build your network through assistance that comes from schools, mental health clinics, and community groups. [substeps] Campus counseling is generally the first steps a college student can take to find career opportunities, school programs, or work. (C) Visit the school counselor's website and receive information about counseling services near you. When you contact the counselor, a menu should come up, with your contact information and a list of students available. (D) If you're having trouble navigating who you are, consider seeking some professional guidance. [substeps] College campuses nowadays almost always have counseling or mental health services.
[A]:
D