Answer:
1) Build walls along steep slopes -> <em>Prevent soil erosion</em>
2) Purify water to remove industrial byproducts and other waste products -> <em>Prevent aquatic ecosystems from declining</em>
3) Introduce tough laws to ban activities such as hunting, fishing, and poaching -> <em>Prevent explotation of species</em>
Explanation:
1) Build walls along steep slopes -> <em>Prevent soil erosion</em>
In steep slopes, the risk of erosion is more elevated in comparison to other land formations. Preventing soil erosion is fundamental to prevent detrimental damage to the environment, infrastructure, and even communities of a certain region. Building walls, terraces, and adding vegetation to steep slopes highly contribute to the prevention of erosion.
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2) Purify water to remove industrial byproducts and other waste products -> <em>Prevent aquatic ecosystems from declining</em>
First and foremost, mitigating aquatic pollution - industrial waste and products - is essential to keep an aquatic ecosystem healthy. In addition, methods of water purification as well as biotechnological application such as the use of bacterial strains that consume pollutants is fundamental to remove industrial waste and prevent the decline of freshwater and marine species.
3) Introduce tough laws to ban activities such as hunting, fishing, and poaching -> <em>Prevent explotation of species</em>
Overhunting and overfishing leads to the decline of economically and ecologically-important species. The introduction of new laws that ban illegal hunting, overfishing, and poaching in addition to natural protected areas lead to the prevention of the explotation of species, enabling them to thrive and reproduce in their habitats.
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