[SC悬赏令] OG18 772关于比较结构的问题~

Heating-oil prices are expected to be higher this year than last because refiners are paying about $5 a barrel more for crude oil than they were last year.

　　(A) Heating-oil prices are expected to be higher this year than last because refiners are paying about $5 a barrel more for crude oil than they were

　　(B) Heating-oil prices are expected to rise higher this year over last because refiners pay about $5 a barrel for crude oil more than they did

　　(C) Expectations are for heating-oil prices to be higher this year than last years’ because refiners are paying about $5 a barrel for crude oil more than they did

　　(D) It is the expectation that heating-oil prices will be higher for this year over last because refiners are paying about $5 a barrel more for crude oil now than what they were

　　(E) It is expected that heating-oil prices will rise higher this year than last yea’s because refiners pay about $5 a barrel for crude oil more than they did

答案是A，能够选对

C的错误之一是this year 和 last year’s 不平行，可为什么不能是今年的价格和last year's比较呢，这样不就平行了么？

求NN解释！