Answer:
Greene uses: A. humor of situation
Impropriety
Over time/ages, there are actions that today can be understood to be acceptable when they were once unacceptable. For instance, the standard actions for young women with regard to their interactions with men used to be quite strict. It used to be considered improper for a young unmarried woman to be alone with a man. This would be considered improper in the nineteenth century when it is completely acceptable today. As such, it was deemed an impropriety.