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<u>Environmental sustainability</u> is the idea of preserving the environment so that it can sustain the future generations. This is a very important concept in human geography because humans all live off of the environment, and to keep our species alive, we need to be able to preserve the environment for the future generations.
Answer A talks about a coal mining method to keep minders from working in underground conditions. Although this is a good thing to do, it is not preserving an aspect of the environment for future generations as it says the main purpose is to help current coal miners, so A is incorrect.
Answer C talks about cutting down trees. While having homes for the future generation is good, it is not preserving the environment at all, so C is incorrect.
Answer D talks about fattening cattle in a way to produce agriculture efficiently and at the lowest cost. While this is good for the current economy, agribusinesses, and farmers, this certain method doesn't have to do with preserving an environmental feature and keeping it sustainable, so D is incorrect.
Answer E talks about the draining of wetlands, which can be detrimental those natural ecosystems. This is not preserving the environment for future generations, so E is incorrect.
Answer B talks about utilizing terracing, which is a farming method where hills are terraced (to be like steps) to prevent soil erosion and just have the crops be watered by the water flowing down the hill. This is definitely going to preserve the soil for future generations and it also mitigates some of the negative effects of irrigation such as water pollution and soil salinization. This matches the concept of environmental sustainability very well, so B. terracing rice paddies on hillsides to prevent soil erosion and provide gravity-fed irrigation is the correct answer.
Have a wonderful day and keep on learning! :D