In a certain society, there are two marriage groups, red and brown. No marriage is permitted within a group. On marriage, males become part of their wives groups; women remain in their own group. Children belong to the same group as their parents. Widowers and divorced males revert to the group of their birth. Marriage to more than one person at the same time and marriage to a direct descendant are forbiddenIf widowers and divorced males retained their group they had upon marrying which of the following would be permissible? (Assume that no previous marriage occurred)

A. A woman marrying her dead sister's husband
B. A woman marrying her divorced daughter's ex-husband
C. A widower marrying his brother's daughter
D. A woman marrying her mother's brother who is a widower.

D is the answer.