The herd boy economy refers to the shepherd boy regardless of the damage to the grassland when grazing. In economics, it is likened to the pursuit of high production (consumption of natural resources) and high consumption (commodity conversion into pollutants). Consumption of natural resources and the selection of environmental pollution caused by waste accumulation. According to the above definitions, Which of the following belong to the shepherd's economy:. ['The excrement of passengers in the spacecraft is processed and purified and converted into oxygen, water and salt for recovery and use by passengers.', 'Pig manure and part of straw are used as raw materials for biogas digesters, and the biogas produced can be used for cooking and lighting.', 'A lot of funds were invested in organizing villagers to plant apple trees in a certain place.', 'In order to increase crop yield in a certain place, a large amount of water, chemical fertilizers and pesticides are consumed, causing pollution of soil and groundwater.']