The correct answer is C. Tin, lead.
Solder is an alloy of tin and lead. It is a low-melting point alloy that is used to join metal objects together. Solder is typically used in electronics, plumbing, and jewelry making.
Lead is a heavy metal that is toxic to humans. It is a major component of solder because it lowers the melting point of the alloy and makes it easier to work with. Tin is a non-toxic metal that is also used in solder because it increases the strength and durability of the alloy.
The other options are incorrect because they do not include tin. Option A is lead and zinc. Option B is copper and lead. Option D is sodium and lead.