Which synonym best describes a person who is not upset during a loud and angry discussion?

This question is incomplete, here´s the complete question

Which synonym best describes a person who is not upset during a loud and angry discussion?

Gentle: lacking harshness or roughness

Quiet: not making noise

Restful: peaceful and quiet in a relaxing way

Unruffled: calm during times of confusion

Unruffled

Explanation:

While the other options do refer to a state of calmness, they don´t inherently provide any connection to a stressful situation such as an intense and impassioned argument.  

Only "Unruffled" implies that that state of tranquility happens in the middle of a surprising or frightening event.

Saying that someone remains unruffled, means that even under a stressful situation they don´t seem to be affected.

union blockade

explanation:

the union blockade in the american civil war was a naval strategy by the united states to prevent the confederacy from trading.

the blockade was proclaimed by president abraham lincoln in april 1861, and required the monitoring of 3,500 miles (5,600 km) of atlantic and gulf coastline, including 12 major ports, notably new orleans and mobile. those blockade runners fast enough to evade the union navy could only carry a small fraction of the supplies needed. they were operated largely by british citizens, making use of neutral ports such as havana, nassau and bermuda. the union commissioned around 500 ships, which destroyed or captured about 1,500 blockade runners over the course of the war.

what are the options ?