According to the lecture, there seems to be a seemingly endless repetition of generation gap between parents and children in the author’s family. It means the generation gap between ________ and that between ________.
选项：

A:the author and his sons; his mother and his sons
B:the author and his mother; his grandpa and his mother
C:the author and his mother; the author and his sons
D:the author and his sons, his grandpa and his mother