How were the coastal plains formed

basically, they start off as continental shelves then the sea level lowers becoming a coastal plain

Explanation:

"To help prevent oil spills" is the one reason among the following choices given in the question why some oil tankers are being built with two hulls. The correct option among all the options that are given in the question is the fourth option or option "D". I hope that this is the answer that has come to your help.