Final answer:
Building dams can negatively affect people by disrupting aquatic ecosystems, altering sediment flow, and increasing the risk of earthquakes. While these factors can have significant environmental and societal consequences, it's worth noting that dams can also promote agricultural development by providing a reliable water supply.
Step-by-step explanation:
Building dams along rivers such as the Nile, Euphrates, and Tigris can be harmful to people for a variety of reasons. The construction of dams leads to the disruption of aquatic ecosystems, as natural water flows and access to habitats are altered, which can reduce or eliminate populations that rely on these natural flow patterns. Additionally, the alteration of sediment flow disrupts the transport of nutrients and the natural cycling processes, potentially leading to decreased soil fertility downstream and impacting agricultural productivity.
Moving further, building dams in seismically active areas can increase the risk of earthquakes due to the added weight of the reservoirs on tectonic plates, which can have catastrophic consequences if they lead to the failure of the dams. However, option (d), the promotion of agricultural development, is generally considered a benefit provided by dams as they can create a reliable water supply for irrigation. But it's important to note that while dams can promote agriculture, the negative impacts on ecosystems and potential risks must be carefully weighed against the benefits.