Task: Question Answering
Input (English): Sulfur (S), oxygen (O2), water (H2O), and sodium chloride (NaCl) are all examples of pure substances. Which of the following describes all pure substances?  
 (A) A pure substance consists of only one type of element. (B) A pure substance has a definite chemical composition. (C) A pure substance cannot be broken down into simpler substances. (D) A pure substance is normally found as a solid at room temperature.
Output (English): B