Answer:
iron and nickel
Explanation:
According to the various researches conducted by numerous scientists, the core of the earth is made of "IRON and NICKEL." The Iron forms the inner most park, with a radius of about 750 miles thickness, while the Nickel-Iron alloy forms the outcome, with a radius of about 1,355 miles thickness.
Hence, in this case, the correct answer is " Scientists believe that the earth's core is made mostly of: IRON and NICKEL.
