Final answer:
In Chinese opera, private troupes owned by scholar-gentries comprised of individuals from the 'base people' group, which included performers who played all the roles, none of the given options (a, b, c, or d) match this historical fact.
Step-by-step explanation:
In Chinese opera, private troupes owned by scholar-gentries featured performers who were categorized under the 'base people' group, a social stratum that included those performing tasks considered less honorable such as music and acting. These troupes would have been made up of individuals who took on all roles within the opera performances. Since the 'base people' included those hereditarily performing tasks like music and acting, the individuals who played all the roles in private troupes owned by scholar-gentries would be part of this group. Due to a lack of specific options provided in the context that match these historical facts, the answer would be none of the provided options (a, b, c, or d).