The correct answer to the Twisting in General quiz is the “Twisting C” video is the only version that exceeds a 1/2 twist.
In Twisting C there is nothing separating the 1/2 twisting entry from the 1/2 twisting rotation by the bases, making the skill a full twist from a rules point of view.
In Twisting A there is a clear stop between the 1/2 twisting entry and the bases rotating an additional 1/2. In this example the bases rotation, following clearly stopping the 1/2 twisting entry, could have twisted in the same stunt position forever without being considered a transition.
In Twisting B there is a change in twisting direction, making the skill a 1/2 twist in one direction, followed by a 1/2 twist in the opposite direction.
In Twisting D there is a dip following the 1/2 twisting entry. The bottom of the dip is a new point of initiation, making the 1/2 to extension a separate skill from the 1/2 twist to prep.
This ruling and explanation are based on the 2016-17 version of the rules dated August 31, 2016.