cassidy does not know for which course she will register. how could a writer best revise the above sentence…

cassidy does not know for which course she will register. how could a writer best revise the above sentence to avoid overly formal language? cassidy does not know which course she will register for. cassidy does not know for which course she will choose to register. cassidy does not know for what course she will register.
Answer
Brief Explanations:
The original sentence has an inverted pre - position structure "for which" which is formal. The first option "Cassidy does not know which course she will register for." moves the pre - position "for" to the end, making it more natural and less formal. The second option adds "choose to" which doesn't reduce formality. The third option "for what" is still somewhat formal and less common in informal speech.
Answer:
Cassidy does not know which course she will register for.