Correct Answer: (d) Nickel and ferrum
Solution:The elements nickel and ferrum are abundant in the formation of Nife, the inner layer of the Earth. Nife is abbreviation of Nickel and Ferrum (Iron). The early core was formed when droplets of iron, nickel, and other heavy metals gravitated to the Earth's center to form the core of the new planet. Relatively buoyant materials, such as silicates, and water, stayed close to the planet's exterior. This process is known as planetary differentiation. The molten material that surrounded the core was the early mantle. Materials that initially stayed in their liquid phase during this process, called "incompatible elements," ultimately became Earth's brittle crust. The crusts are still evolving due to plate tectonics. Water held within minerals erupted as lava, a process known as "outgassing." As more water was expelled, the mantle solidified.