I am pretty sure it's C. Insulator.
An element is also a pure substance. The reason for this is because an element contains only one type of particle.
Option A is correct
They exhibit considerable molecular complexity and diversity
Alpine Tundra are found at the tops of tall mountains.
And it differs because the <span>Arctic refers to Northern latitudes, alpine refers mountainous regions.</span>
A. umbilical cord is the answer
