Final answer:
Mark and Mary Anne compromised, which typically leads to a resolution and the development of a friendship when common goals are involved. Sociological research supports that proximity fosters friendship. Considering the prompt, the best answer is that they became 'Friends'.
Step-by-step explanation:
When Mark compromised with Mary Anne, they reached an agreement or found a middle ground in their relationship.
Considering the various possible outcomes of a compromise, if two individuals manage to resolve their issues and begin to work together by the necessity to defeat common enemies, this often leads to the development of a friendship.
This is also supported by sociological research, which suggests that people who live close to each other, such as in the same apartment building or neighborhood, have a higher chance of becoming friends due to proximity and the opportunity for repeated interactions.
Conversely, if the situation was filled with tension, like the one described between Marjorie and Bernice, where they are 'half-angry, half-afraid', this could lead to a neutral stance or even animosity, rather than friendship, after a compromise.
Nevertheless, the prompt hints that Mark and Mary Anne have resolved their differences amicably, thus making 'Friends' the most likely choice for the fill-in-the-blank question.