Final answer:
The correct answer is that the wind direction at Charleston is consistent with the counter-clockwise wind flow around a low-pressure system as demonstrated by the hand-twist model. Hence, the correct answer is option (a).
Step-by-step explanation:
The wind direction at Charleston is consistent with the wind flow of the hand-twist model around a low-pressure center. This can be understood by referencing how wind behaves around areas of low pressure due to the Coriolis effect, causing it to move counter-clockwise in the Northern Hemisphere.
In the provided text, a change in wind direction from northeast to southeast suggests that the movement is consistent with the counter-clockwise flow around a low center, as would be the case in a hand-twist model. Therefore, the correct answer would be: 'The wind direction at Charleston is consistent with the wind flow of the hand-twist model around a Low center.'