Among the important themes that characterize Chinese history are the p

Among the important themes that characterize Chinese history are the patterns of dynastic rise and fall, intermittent aggression from northern aliens, and varying degrees of openness to outside cultural influences and the dynamics of stability and social harmony

A. Among the important themes that characterize Chinese history are the patterns of dynastic rise and fall, intermittent aggression from northern aliens, and varying degrees of openness to outside cultural influences and the dynamics of stability and social harmony

Incorrect. "and varying degrees of openness .. and the dynamics ... " is not correct. For this to be correctly listed as one element in a list, varying degrees of [openness to outside cultural influences] and [x] have to be parallel. Here, "the dynamics of stability and social harmony" attempts to incorrectly parallel "openness to outside cultural influences". Perhaps removing the "the" before dynamics corrects this.

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

Correct. B averts the problem in A, where too much content has been jammed in the last element of a set. The first set of {"patterns of dynastic rise and fall" and "intermittent agression"} is clearly separated and rather elegantly paralleled to the second set of {"varying degrees of openness" and "dynamics of stability and social harmony"}, each of which in itself is parallel.

C. The important themes that characterize Chinese history are the patterns of dynastic rise and fall, intermittent aggression from northern aliens, along with varying degrees of openness to outside cultural influences and the dynamics of stability and social harmony

Incorrect. Changes the meaning by omitting the "among".

D. Among the important themes of Chinese history are the patterns of dynastic rise and fall, intermittent aggression from northern aliens, varying degrees of openness to outside cultural influences and the dynamics of stability and social harmony that characterize its history

Incorrect. Changes the meaning by misplacing the "characterize its history" at the end, suggesting that the previously listed elements do not characterize history.

E. The important theme that characterizes Chinese history is the pattern of dynastic rise and fall, intermittent aggression from northern aliens, along with varying degrees of openness to outside cultural influences and the dynamics of stability and social harmony

Incorrect. Subject and verb do not agree. "Important theme" and goes on to list multiple items.