Which is a reactive a.) silicon b.) sodium c.) chorine d.) argon

Sodium is very reactive but it’s a metal, and the problem asks specifically for a non-metal.
Silicone is technically reactive, but not super reactive.
Argon is a nonmetal, however it is an inert gas. It doesn’t react with anything.

We’re left with Chlorine, which is a non-metal in group 7, a highly reactive group, on the periodic table.

Rn in the right answer