What is the two-letter postal abbreviation for South Carolina?

In what year did Rhode Island ratify the U.S. Constitution? What is the official nickname of Rhode Island? What is the state bird of Rhode Island? What is the state flower of Rhode Island? Which state uses the postal abbreviation "SC"? Columbia is the capital of which state? What is the largest city in South Carolina by population? In what year did South Carolina ratify the U.S. Constitution?