Given the task definition and input, reply with output. 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". 

[header] How to calculate blood alcohol level [title] Understand what blood alcohol content (bac) means. [step] Blood alcohol content is a measurement of the amount of alcohol in your body. So, a bac of 0.10% means 1 part alcohol for every 1000 parts of blood. <sep> (A) To calculate total bac, multiply it by 1% to get around your bac values. A bac of 0.10% is considered high alcohol content. (B) [substeps] The higher the bac, the higher the risk of becoming elevated. Therefore, av is the most dangerous level of alcohol in your body because it can affect your body's ability to process copper. (C) It is often used for legal or medical purposes, like when determining if you've had too much to drink and drive. [substeps] A bac of 0.08%, often the legal level, indicates that you have 80 mg of alcohol per 100ml of blood in your body. (D) The bac is a measurement of the number of grams of high alcohol content. By operating on a bac, you can calculate the bac's relative percentage of blood alcohol content in your body.

C