[求助]OG119--OG给的E 的解释我有一些疑惑

119. Executives and federal officials say that the use of crack and cocaine is growing rapidly among workers, significantly compounding the effects of drug and alcohol abuse, which already are a cost to business of more than $100 billion a year.

(A)significantly compounding the effects of drug and alcohol abuse, which already are a cost to business of

(B)significantly compounding the effects of drug and alcohol abuse, which already cost business

(C)significantly compounding the effects of drug and alcohol abuse, already with business costs of

(D)significant in compounding the effects of drug and alcohol abuse, and already costing business

(E)significant in compounding the effects of drug and alcohol abuse, and already costs business

Choice B, the best answer, uses clear and concise phrasing to state that it is the effects of drug and alcohol abuse that already cost business the sum mentioned. In A, to business is awkwardly and confusingly inserted between cost and the prepositional phrase that modifies it, and are already a cost to business is wordy and awkward compared to cost business. In C, already with business costs of... is awkward and unclear, failing to specify that those prior effects generate the cost. Choices D and E produce faulty constructions with the phrase significant in compounding, which cannot grammatically modify the verb form is growing

这题的答案是B 同意

但关于OG给的E 的解释我有一些疑惑

significant in compounding the effects of drug and alcohol abuse若用来解释

worker , 句意应该也通是吗 ? 后面 , and costs 也符合主动词一致

请问判别E出局还有其它关键吗 ? 谢谢指教