The section presents a question related to the electrical conductivity of different elements. It asks which element has the lowest electrical conductivity among the options provided. The options include:

A. Aluminum (Nhôm)  
B. Mercury (Thủy ngân)  
C. Stone (Đá)  
D. Lead (Chì)  

Key topics include electrical conductivity and the comparison of various materials. The entities involved are the elements aluminum, mercury, stone, and lead.