The passage characterizes Rosemary as an individual who stands out within her historical context, particularly for her choices that reflect the changing roles of women in the early 20th century. The most fitting response based on the text is:
She is unusual in the upper class of society because she invites artists to her parties.
This choice highlights her preference for mingling with artists and "quaint creatures," which contrasts with traditional upper-class social circles focused on wealth and status. It indicates her embracing of modern ideas and forms of expression, aligning with the period in which Mansfield was writing.