The question came up at the meeting ---- we had not enough m

这句话的意思是：会议上提出了我们是否有足够的钱来做这个调查的问题.
这句话中we had not enough money for our research作的是The question的同位语,if和whether的一个区别就是if不能用在同位语从句中,所以不用if.
what为关系代词,引导从句时要在从句中充当句子成分,we had not enough money for our research这句话中显然不缺成分 所以也不能用what.
选that也正确,因为that也可以引导同位语从句