Answer:
I had never lived in such a big city.
Explanation:
An independent clause is a clause that makes sense by itself and is a complete sentence. All the other causes are dependent clauses as they can not stand alone.
Hope that helps.
His proclamation changed the minds of many Americans who supported the war in Vietnam which caused many politicians to change their views on the war as well. A famous example would be Lyndon B. Johnson who decided not to run for another mandate.