英语单选～

Beyond determination, courage, and vision, I look foe students with a growing sense of confidence. For iI know from experience that confidence is _____ necessary credential that _____ college students must take away with them.
A. a , most B. the one, all C. one, all D. the, many
答案是B ,但是我不太理解THE ONE NECESSARY CREDENTIAL 是什么意思,觉得A NECESSARY CRREDENTIAL 还能理解点,请高手指教啊

英语单选 一道英语单选～ 一个单选英语 英语单选求助？ 问两道英语单选 中考英语单选 关于英语单选 英语单选问题～ 英语单选~ 英语单选，解释一下