the journey around the world cost them one million dollars,____ more than 40% was spend on food.

这道题目选择B.
基数词,不定代词,表示数量的名词后跟of whom或者of which,表示的是部分概念,比如：
The textile mill has over eight thousand workers and staff,eighty percent of whom are women.
John gave several reasons,only a few of which were valid.
The teacher discussed Jim,one of whose problems was his poor study habits.
这句话的意思是：“环球旅行花了他们一百万元美金,其中的百分之四十花在了吃饭上面.”
希望我能帮助你解疑释惑.40% of one million dollars 一百万美金的百分之四十 这个对吗对的，这里的of就是表示包含或者部分的概念。希望我能帮助你解疑释惑。