A．They found a way to protect livestock from harsh weather in their regions.
B．They realized that a moving lifestyle offered benefits that outweighed the hard work.
C．They had to learn the area due to a rapid increase in population.
D．They learned that growing crops is possible in the southern regions.
A．Landfills should be expanded to accommodate more types of waste.
B．Landfills are not a suitable long-term solution for solid organic waste disposal.
C．Landfills should be built farther away from population centers.
D．Landfills would be an effective means of recycling solid organic waste from farms.
A．It is an economical way to process solid waste.
B．It is practical only for treating large amounts of solid waste.
C．It is not an efficient way to process solid waste.
D．It could reduce the cost of treating wastewater.