一道寂静里的语法

Plants are more efficient at acquiring carbon than are fungi, in the form of carbon dioxide, and converting it to energy-rich sugars.

1. Plants are more efficient at acquiring carbon than are fungi
2. Plants are more efficient at acquiring carbon than fungi
3. Plants are more efficient than fungi at acquiring carbon
4. Plants, more efficient than fungi at acquiring carbon
5. Plants acquire carbon more efficiently than fungi

这题我选A 答案是C NN解释下