GRE Sample Test 1 Verbal Reasoning 2

Take note of the time transition at one time inseparable…now, which indicates that the combined roles in Middle Eastern music are now not inseparable. You need a word that means divide or separate. Divulge starts with the proper root, but its meaning is way off.
Meanwhile, neither retreat nor retrench means divide, while fuse is the opposite of what you want. Diverge is the correct answer.