请教GWD5-Q30!

请教一道逻辑题~

GWD5-Q30:

Which of the following most logically completes the argument?

The irradiation of food kills bacteria and thus retards spoilage.  However, it also lowers the nutritional value of many foods.  For example, irradiation destroys a significant percentage of whatever vitamin B1 a food may contain.  Proponents of irradiation point out that irradiation is no worse in this respect than cooking.  However, this fact is either beside the point, since much irradiated food is eaten raw, or else misleading, since _______.

A.    many of the proponents of irradiation are food distributors who gain from food’s having a longer shelf life

B.    it is clear that killing bacteria that may be present on food is not the only effect that irradiation has

C.    cooking is usually the final step in preparing food for consumption, whereas irradiation serves to ensure a longer shelf life for perishable foods

D.    certain kinds of cooking are, in fact, even more destructive of vitamin B1 than carefully controlled irradiation is

E.     for food that is both irradiated and cooked, the reduction of vitamin B1 associated with either process individually is compounded

说irradiation破坏营养，则指出它并不比cooking更损耗营养并不能抹煞irradiation破坏营养的事实，因为，这两个过程如果不同时进行的话，则该比较无意义（离题）；而若这两个过程同时进行的话，则损失的营养是其相加，把他们相互比较也没有意义。

我本来选的是C,答案是E，我做了上述的考虑，但还是觉得不能完全说服自己，主要问题在于，besides the point and misleading是什么意思呢，为什么为有这样的评价呢，其中的逻辑关系我还没有搞清楚~

请教各位！

irradiation的支持者说, irradiation和cooking一样, 都破坏营养, (意思就是irradiation没啥不好, 反正cooking也要破坏营养的)

但是事实是, ____ (这个需要补充, 明显的思路就是, 要反驳上述支持者说的话, 说i和c不一样, 也就是说irradiation不好)

这个用来一个either...or...的并列, besides the point 和else misleading都看作修饰成分, 是说离题和误导, 不影响意思和答案的选择,

简单意译一下就是,

1.根本不是那么回事,因为很多被irradiated过的食物都是生吃的 (反驳了支持者的话, 这是原文, 后面一点用or并列的, 找一个能削弱支持者话的就是答案)

2.这明显就是误导, 那些既需cook, 又被irradiated的食物, 营养成分被减少了两次 (意思还是说irradiation不好, 所以是答案)