Which of the following elements is strictly a non-metal: Silicon, Carbon, Lead, Tin?

• Silicon (Si) is a metalloid, exhibiting properties of both metals and non-metals.
• Carbon (C) is a non-metal, found in various forms like diamond and graphite.
• Lead (Pb) is a metal, specifically a heavy metal.
• Tin (Sn) is a metal, a post-transition metal.

Based on their classifications, Carbon is the only element among the options that is strictly a non-metal.

The final answer is $\text{Option B: Carbon}$.