Though viewed from a distance, Saturn's main rings may appear to be smooth and continuous, they are in fact composed of thousands of separate icy ringlets when viewed up close.
Though viewed from a distance, Saturn's main rings may appear to be smooth and continuous, they are in fact composed of thousands of separate icy ringlets when viewed up close.
Though Saturn's main rings may appear smooth and continuous when viewed from a distance, they are in fact composed of thousands of separate icy ringlets when viewed up close.
Saturn's main rings, when viewed from a distance, may appear to be smooth and continuous, though when viewed up close they are in fact composed of thousands of separate icy ringlets.
When viewed from a distance, Saturn's main rings may appear smooth and continuous, but closer viewing reveals them to be composed of thousands of separate icy ringlets.
Though composed of thousands of separate icy ringlets if viewed up close, the main rings of Saturn may appear smooth and continuous when they are viewed from a distance.
The explanation says that D is the correct answer. I understand that D clarifies the meaning of the sentence, but D is not parallel. Shouldn't D follow a form like: When viewed from a distance...but when viewed more closely"...? As opposed to "when viewed from a distance...but closer viewing...?
I guess the abstract question here is: when is it necessary for a sentence to remain parallel and when is it not?
Thanks for all your help