How to do 18,19 and 20 with steps please

Ibelieve the answer is d. densityhope my answer has you : )

The geological theory that states that pieces of earth's lithosphere are in constant slow motion is the theory of plate tectonics.

Im not from america so could you explain what route 70 is? how much km or miles does it have? am i supposed to know ,from this text,what the s(road) is? how many km or miles it has?

Answer increases the risk of developing genetically influenced diseases;