During the eighteenth century, widespread changes in agriculture, known as the agrarian revolution, involving the large-scale introduction of enclosed fields, of new farming techniques and crops, and the substitution of commercial for subsistence farming.
A: revolution, involving the large-scale introduction of enclosed fields, of new farming techniques and crops, and
B: revolution, involved the large-scale introduction of enclosed fields and of new farming techniques and crops, and
C: revolution, which involved the large-scale introduction of enclosed fields and of new farming techniques and crops, and
D: revolution involved the large-scale introduction of enclosed fields, new farming techniques and crops, and of
E: revolution that involved the large-scale introduction of enclosed fields and new farming techniques and crops, and of
这道题答案是B是因为widespread changes 做主句主语,involved做谓语,其余选项都缺谓语吧.请指教. | 
