大全476 关于比较结构在句首的问题

1.        Less detrimental than the effects of bacterial transformation is the effects of bacterial deterioration: spoilage of food, metals corroding, decay of wood, and other undesirable alterations of substances.

(A) is the effects of bacterial deterioration: spoilage of food, metals corroding

(B) are the effects of bacterial deterioration: spoilage of food, metals corroding

(C) is the effects of bacterial deterioration, which include spoilage of food, metals corroding

(D) are the effects of bacterial deterioration, which includes spoilage of food, corrosion of metals（E）

(E) are the effects of bacterial deterioration: spoilage of food, corrosion of metals

请NN们指教一下这题的语法点，为什么谓语用复数而不是单数，请详细说明或提供相关键连，i have no idea about this, a lots of thanks!

i gor it:

the effects of bacterial deterioration are Less detrimental than the effects of bacterial transformation

is that right?