The best alternative title for the passage will be______.

A．depends on climate and soil type in a virgin environment undamaged by human beings
B．was greatly affected by human beings before they started using chemical substances on the soil
C．was radically transformed by uncivilized human beings
D．refers to plants, trees, climate, type of soil and the ecological environment

A．Because they are the weeds that cannot be eradicated by herbicides.
B．Because all selective herbicides can encourage the growth of previously unimportant weeds by eliminating their competitors.
C．Because they were hardly considered before so that their seeds were not prevented from germinating.
D．Because they benefit greatly from the fertilizer applied to the farm lan