The correct option is B Among the important themes that characterize Chinese history are the patterns of dynastic rise and fall, and intermittent aggression from northern aliens, together with varying degrees of openness to outside cultural influences and the dynamics of stability and social harmony
Let P be 'the patterns of dynastic rise and fall', Q be 'intermittent aggression from northern aliens', R be 'varying degrees of openness to outside cultural influences', S be 'the dynamics of stability and social harmony'.
A. Incorrect, P,Q,R & S cannot be parallel simultaneously as they belong to different clause category.
B. Correct. P is parallel to Q, [connector] R is parallel to S
C. Incorrect. Here Q follows P but is not separated by parallel marker "and". R is parallel to S.
D. Incorrect. Same as A. Also the phrase "the dynamics of stability and social harmony that characterize its history" changes the intended meaning of "themes that characterize its history"
E. Incorrect. Same as C