What does the C mean on items?

Excuse me, could you please clarify what the "C" stands for on these items? I've noticed it on a few products and I'm wondering if it represents a specific certification, category, or something else entirely. It's important for me to understand the significance of this marking before making a purchase. Could you elaborate on the meaning of the "C" and how it relates to the products in question? Thank you for your assistance.