I can't see any of the other options, but I'll give you the basic definition of government according to the U.S. Constitution:
Government is in place "to establish justice, insure domestic tranquility, provide the common defense, promote the general welfare, and secure the blessings of liberty to ourselves and our prosperity".
In a nutshell, government is there to protect the rights of the people, nothing else. Not sure what they gave you on your question, but I hope this helps!