By explaining problems and giving solutions! this is the best fit because the other two might make sense at a first glance, but only explaining problems and solutions would be an effective way to teach people how to set up an aquarium by giving them examples of what to do and what not to do whereas the others are just him talking about his aquarium.
We have experienced many hardships for example racism. In to kill a mocking bird racism was very popular. In the last few months racism has become popular again. People have been killed because of there color.