Answer:
Option D: Fluorine
Step-by-step explanation:
From the periodic table, Nickel and Sodium are metals. Which means that they are good conductors of electricity.
While silicon is a metalloid. A metalloid has properties of both metals and nonmetals. Thus, it has tendencies to conduct electricity.
Fluorine is a non - metal which means that it doesn't conduct electricity.
Thus, the most likely that is not a good conductor is Fluorine.