The section presents a question related to chemistry, specifically about the elements found in table salt (muối ăn). The question asks which element is present in salt, providing four options: A. Potassium (Kali), B. Sodium (Natri), C. Calcium (Canxi), and D. Magnesium (Magie). The key topic is the identification of elements in common compounds, with a focus on table salt. The main entity involved is sodium, which is the correct answer.