What is the meaning of the oxymoron courageous retreat in this excerpt?

the firefighters were stuck. they had given all they could to prevent the fire from spreading, but they were having little success. and the fire was closing in around them. to avoid possible casualties, the firefighters made a courageous retreat out of harm’s way.

because the two words are opposites, together they emphasize the idea that the firefighters are heroes.

although the two words are opposites, together they convey the idea that the firefighters’ decision to retreat is justified.

because the two words are opposites, together they emphasize the idea that the firefighters’ decision to retreat is suspicious.

although the two words are opposites, together they convey the idea that the firefighters acted selfishly.