[問題]pp test1 103 structure

[silvery]

The United States national debt was relatively small until the Second World War, during when it grew from $43 billion to $259 billion in just five years.

我知道答案是選c
只是我不知道要怎麼改才會正確
因為during後面不能加動詞 所以把when改掉也不對
假如可以選的話 那我會選擇把during刪掉
所以我想請問各位 請問這一題要怎麼改比較好呢
謝謝大家~~~

[Bill]

應該改成which!!!

[silvery]

謝啦~~~大感謝