All elements to the left of the staircase line in the periodic table are classified as c) metals.
This classification includes elements that typically exhibit metallic properties such as high electrical and thermal conductivity, malleability, and ductility. Metals are usually solid at room temperature (with the exception of mercury) and tend to lose electrons during chemical reactions, forming cations. Understanding the arrangement of elements on the periodic table helps in identifying their chemical and physical properties, allowing for a clearer insight into their classification.