The reason that Thomas Paine brings up the opposing argument that the colonies have been well protected by the British is:
B. To create a chance to prove his opponents wrong
Thomas Paine states in “The American Crisis, No.1" about the importance of Independence for the people of America. He approaches every people through emotional thoughts and ideas. His writings persuade people to think over the need for Independence of themselves and for their children. Thomas Paine didn’t agree with the fact that Great Britain has always benefited the colonies and will ever benefit them in the future. He opposes the fact that it will provide security and protection to the colonized countries.
There is an archaic term "Exeunt" used to describe a situation where many characters leave the stage. "Exeunt Omnes" would be the stage direction for everyone to leave.