The section presents a question related to the periodic table, specifically focusing on the halogen group of elements. It asks which halogen has the largest atomic number among the given options. The options provided are:

A. Fluor (Fluorine)  
B. Clo (Chlorine)  
C. Brom (Bromine)  
D. Iot (Iodine)  

Key topics include the classification of elements in the periodic table and the properties of halogens. The entities involved are the four halogen elements listed.