IF ANYONE IS FRIENDED WITH bob AND SOME NUMBERS (like a lot of them) HE IS MY BSF AND AND MY OLD ACCT GOT DELETED FOR NO REASON AND AND I NEED MY BSF BACK PLEASE HELP A GIRLY OUT!!

How did inca develop their road system? a) they used mortar to hold the stones together.b) they built suspension bridges over rivers. c) they mixed copper and stone together to make the blocks.d) they laid roads in the cities, not in the less densely populated deserts.