Final answer:
A southerly wind means the wind is blowing from the south towards the north, so the correct answer is C. North.
Step-by-step explanation:
When meteorologists talk about wind direction, they are referring to the direction from which the wind is coming. Therefore, a southerly wind means that the wind is coming from the south and blowing toward the north. The correct answer to Rachel's question is C. North, as this is the direction the wind blows towards when there is a southerly wind.