SAT语法,关于主语和宾语是否要同单复数（谓语是be动词时）

题目

SAT语法,关于主语和宾语是否要同单复数（谓语是be动词时）
A)The disposal of nuclear fission's unwanted by-products is one of the problems.
B)Unwanted by-products of nuclear fission that need to be disposed of are one of the problems
解释里说是disposal和后面的one一致,但是我也看到过主语是复数,谓语宾语是单数的情况啊.
如果B要改是否要改成Unwanted by-products of nuclear fission that need to be disposed of are manyl of the problems
就是Unwanted by-products are problems.The unwanted by-product is one problem对不对？
比如The color is a problem of the nasty painting.

答案

这题我做过.
Unwanted by-products are problems,Unwanted by-products is one problem都说不通应该不对.比如说“死鱼是问题”这话说的通吗?没有讨论意义.
但是即使语法改对了,这句话还是要选A.
这是IS题啊同学.语法都对,还要比那个选项更合理.
因为B选项改变了句意.by-products不是problems.
The disposal of by products才可以说是一个problems.
所以B选项从语法和选项合理性上都说不通.