Pretty sure its c. From the text you provided me
Hello friend,
if i am not wrong crust is believed to generate its magnetic field..
hope that helps u
The world's tallest artificial structure is the 829.8-meter-tall (2,722 ft) Burj Khalifa<span> in Dubai. The building gained the official title of "Tallest Building in the World" and the tallest self-supported structure at its opening on January 9, 2010.</span>
