Task: Text Completion
Input (English): [header] How to study chemical reactions and their thermodynamic parameters [title] Define a chemical reaction. [step] A chemical reaction involves bond breaking and bond formation. In order to understand a chemical reaction, one needs to understand the meaning of a chemical bond. <sep> (A) As an example we take the hydrogen molecule. This molecule is stable enough to exist and has one sigma bond between its hydrogen atoms. (B) Basic law of chemical relationships between atoms atoms helps us understand the theoretical state of a particular atom after it is applied to a molecule. Understanding the context will help us understand chemical reactions differently. (C) The start button of a chemical exchange is always identified with a symbols near the beginning. [substeps] The initial area of the equation to learn about this can be the path for the reaction that is occupying space and processing the energy of the chemical. (D) Do this by doing a series of equations that outline the problem. This must be explained within each one to make sure that it is explaining logically.
Output (English): A