What is the drawing technique of using that to create degrees of shading or solidity instead of using lines

Stippling is the drawing technique of using dots to create degrees of shading or solidity instead of using lines.

option c (nickel) is not found in earth's crust. the earth's crust basically contains eight (8) elements namely: oxygen, silicon, aluminum, iron, calcium, sodium, potassium and magnesium (listed in order of abundance).

eurasia because it is europe and asia