Answer:
a. protein
Explanation:
Copper is an essential mineral because our body cannot produce it on its own and we need it to live. The major sources of copper includes protein rich foods such as liver, oysters, crab, shellfish, nuts, spinach, Shiitake mushrooms, etc. Most of these foods also contain healthy fats, e.g. almonds, nuts and legumes. Even some fruits contain copper but on very small amounts, e.g. tomatoes.
