<span>The United States had troops in Saudi Arabia</span>
I believe it’s improved transportation
"De facto" means "in fact, factually" - that something is, indeed, taking place. It is customarily used to denote a situation which is not dictated by law ("de jure") but which happens anyway - so the best answer is A. Law - this segregation is not required by law, but it takes place anyway, for example for financial reasons.
<span>The Constitution is the document that describes the plan of government for the United States including its purpose and structure. This is your answer! </span>
