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 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.
Example Output: C

Example Input: Some texts pops up on the screen. A video of bulls being hurt by people starts playing. text <sep> (A) pops up on the screen again. (B) switches to clips of bulls running away from the camera. (C) shows up of a youtube video. (D) goes onto the screen that say something about feeding bulls and how to lift their horns.
Example Output: A

Example Input: [header] How to study without looking at books or notes [title] Know what type of a learner you are. [step] There are three types of learners: visual, auditory and kinesthetic. [substeps] Visual learners learn by looking at charts or graphs. <sep> (A) Kinesthetic learners understand the magnetic properties of the material they're studying by looking at an instrument in response to movement. Auditory learners understand the musical concepts of the material they're studying. (B) An auditory learner thinks through the topics presented. Kinesthetic learners will write down and study content presented on a spreadsheet or in a textbook. (C) Auditory learners learn by looking at vocabulary objects. Kinesthetic learners study as a group, not the entire class. (D) Using colorful posters that are full of information, mind maps or flashcards tends to work best for visual learners. Try using flashcards and write your notes in a colorful way.
Example Output:
D