Concept:The Earth’s inner core is made up chiefly of metallic elements, mainly iron and nickel.Explanation:The inner core is the deepest and hottest layer of the Earth.It exists in a solid state because of the enormous pressure acting upon it.This layer is composed largely of iron, with a significant proportion of nickel.Together, these two metals form the bulk of the inner core.The other options contain elements or minerals that are not the main components of this layer.Answer:B. iron and nickel