The most appropriate step ordinary people can take to minimize the effects of earthquakes and volcanoes and prevent the loss of human life is:
D. They can follow all advice and directions of first responders.
Following the instructions of first responders is crucial during and after natural disasters, as they are trained to handle such situations and can provide the best guidance to ensure safety and minimize risk.
While other options may seem relevant, they either involve actions that are not practical for ordinary individuals (like using scientific equipment) or are not proactive steps (like creating an emergency plan after a disaster has started).